Modem Disconnecting

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Brady_ls
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Modem Disconnecting

Post by Brady_ls »

Hi All,

My connection keeps dropping out. Below is a copy paste of my log. Does this mean that the modem is disconnecting from the router, or that modem is disconnecting from the network?

Code: Select all

Sat Apr 14 21:02:20 2018 : Modem #1 Connected (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 21:03:23 2018 : Disconnect (Removed) Modem #1
Sat Apr 14 21:03:46 2018 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 21:03:51 2018 : Modem #1 Connected (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 21:04:29 2018 : Disconnect (Removed) Modem #1
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Re: Modem Disconnecting

Post by JimHelms »

It appears to be connecting and immediately disconnecting.

First, make sure the correct APN is entered in MODEM >> CONNECTION INFO >> APN and there are no blank spaces behind the APN.

Next, go to MODEM >> DEBUG INFORMATION >> AT COMMANDS and copy and paste what it is showing.
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Re: Modem Disconnecting

Post by Brady_ls »

I tried re-flashing firmware and Configuring the MC7455. Same issue, but here is connection log and debug info from after ding this.

Code: Select all

Sat Apr 14 22:40:29 2018 : Modem #1 Connected (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 22:41:10 2018 : Disconnect (Removed) Modem #1
Sat Apr 14 22:41:31 2018 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 22:41:37 2018 : Modem #1 Connected (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Sat Apr 14 22:44:13 2018 : Disconnect (Removed) Modem #1

Code: Select all


Sat Apr 14 22:45:10 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
OK
  
Sat Apr 14 22:51:28 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
OK
  
Sat Apr 14 23:18:36 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
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Re: Modem Disconnecting

Post by Cheburashka »

I am having the same issue. I'm totally clueless at this point as to what is happening. I know the router is working - if I plug in a USB hotspot into it, it connects, but it doesn't connect with the MC7455. Had random disconnects, now did a full reset of both router and MC7455 and not being connected at all. GSTATUS shows status as online:

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  681		Temperature: 39
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      B26    		LTE bw:      5 MHz   
LTE Rx chan:   8763		LTE Tx chan: 4294967295
LTE CA state:  NOT ASSIGNED
EMM state:     Deregistered   	Attach Needed  
RRC state:     RRC Idle       
IMS reg state: No Srv  		

PCC RxM RSSI:  -85		RSRP (dBm):  -106
PCC RxD RSSI:  -80		RSRP (dBm):  -101
Tx Power:      0		TAC:         5412 (21522)
RSRQ (dB):     -6.5		Cell ID:     0A814E0B (176246283)
SINR (dB):     19.4
Log is similar to yours:

T

Code: Select all

ue Oct 17 17:47:33 2017 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Tue Oct 17 17:48:42 2017 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Tue Oct 17 17:50:26 2017 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated Sierra_Wireless_MC7455_Qualcomm®_Snapdragon™_X7_LTE-A)
Tue Oct 17 18:03:49 2017 : Disconnect (Removed) Modem #1
Tue Oct 17 18:05:26 2017 : Attempting to Connect Modem #1 (Sierra_Wireless,_Incorporated 
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Re: Modem Disconnecting

Post by Cheburashka »

I have also put the SIM card in the hotspot it came with (Sprint/Calyx) and LTE is working fine.
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Re: Modem Disconnecting

Post by JimHelms »

Brady_ls wrote: Sat Apr 14, 2018 6:24 pm I tried re-flashing firmware and Configuring the MC7455. Same issue, but here is connection log and debug info from after ding this.

Sat Apr 14 23:18:36 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
The logs you posted really does not tell much other than showing r.ispsn is the APN you are trying to connect to the network with. Need to copy and past the reset of the information with the antenna signals that will be in that same window.

I also assume your APN is r.ispsn on your hotpot as opposed to n.ispsn?
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Re: Modem Disconnecting

Post by JimHelms »

[quote=Cheburashka post_id=59 time=1523775333 user_id=122]
I am having the same issue. I'm totally clueless at this point as to what is happening.
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Re: Modem Disconnecting

Post by JimHelms »

There is a step by step tutorial HERE to troubleshoot disconnects. It covers the vast majority of these type of issues. And it is most always something simple being overlooked.
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Re: Modem Disconnecting

Post by Cheburashka »

Hi Jim, you're totally right. One of the pigtails wasn't attached well to the MC7455, which explains the periodic signal drops.

Argh, spend 2 hours last night trying to diagnose/fix when it was something this simple!

Thanks again!
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Re: Modem Disconnecting

Post by JimHelms »

Cheburashka wrote: Sun Apr 15, 2018 5:02 pm Argh, spend 2 hours last night trying to diagnose/fix when it was something this simple!
That is often the case. Glad you got it up and running.

Again, I encourage anyone having disconnection issues to go through the check list on the tutorial. Chances are, it is there you will discover your fix.
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Re: Modem Disconnecting

Post by Cheburashka »

Actually I'm back to periodic disconnects.. :(

When it disconnects, it looks like the router admin page is also inaccessible.

I'll try cleaning the SIM card as well, although not sure how it could become dislodged.
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Re: Modem Disconnecting

Post by Jflex113 »

Do you have the modem reconnect enabled? If you have it set to router reboot during a lose of ping then that can happen.

It should look like this when enabled with modem reconnect if you are using it.

Modem Reconnect 1.jpg


If the router reboots every time you loose internet connection then this setting (if it is selected) could be your issue.

Modem Reconnect 2.jpg


I would check this to eliminate one possible cause of the router not being accessible during a lose of internet.
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Re: Modem Disconnecting

Post by Brady_ls »

JimHelms wrote: Sun Apr 15, 2018 7:17 am
Brady_ls wrote: Sat Apr 14, 2018 6:24 pm I tried re-flashing firmware and Configuring the MC7455. Same issue, but here is connection log and debug info from after ding this.

Sat Apr 14 23:18:36 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
The logs you posted really does not tell much other than showing r.ispsn is the APN you are trying to connect to the network with. Need to copy and past the reset of the information with the antenna signals that will be in that same window.

I also assume your APN is r.ispsn on your hotpot as opposed to n.ispsn?



Hi Jim,

I ran through each step in the troubleshooting, and no dice... my APN is the r.ispsn not n.

Here is the copy paste from debug....

Code: Select all

Current Time:  1483		Temperature: 21
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      B25    		LTE bw:      10 MHz  
LTE Rx chan:   8640		LTE Tx chan: 4294967295
LTE CA state:  NOT ASSIGNED
EMM state:     Deregistered   	Attach Needed  
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -76		RSRP (dBm):  -109
PCC RxD RSSI:  -75		RSRP (dBm):  -106
Tx Power:      0		TAC:         5001 (20481)
RSRQ (dB):     -14.8		Cell ID:     0A001700 (167778048)
SINR (dB):     -2.6
OK

Code: Select all

Thu Apr 19 02:34:08 2018 : /dev/ttyUSB1 AT+CSQ
+CSQ: 19,99
OK
AT*CNTI=0
+CME ERROR: no network service
AT!SELRAT?
!SELRAT: 06, LTE Only
OK
AT+ECIO?
+ECIO: NOT IMPLEMENTED
OK
AT+RSCP?
+RSCP: NOT IMPLEMENTED
OK
AT!UMTSCHAN?
!UMTSCHAN: NOT IMPLEMENTED
OK

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  1494		Temperature: 21
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      B26    		LTE bw:      5 MHz   
LTE Rx chan:   8763		LTE Tx chan: 4294967295
LTE CA state:  NOT ASSIGNED
EMM state:     Deregistered   	Attach Needed  
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -66		RSRP (dBm):  -96
PCC RxD RSSI:  -67		RSRP (dBm):  -102
Tx Power:      0		TAC:         5001 (20481)
RSRQ (dB):     -15.6		Cell ID:     0A001F10 (167780112)
SINR (dB):     -1.6
OK
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Re: Modem Disconnecting

Post by Brady_ls »

Modem> Network Status> General Information> Modem jumps between "Sierra Wireless, Incorporated MC7455" and "no modem present."

"Does no modem present" refer to communication between the router and the card?
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Re: Modem Disconnecting

Post by Jflex113 »

Is your modem inside a router like a ZBT or is it in an enclosure? If it is in an enclosure I'm wondering if the usb cable is not good enough and that might be causing these disconnects possibly.
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Re: Modem Disconnecting

Post by JimHelms »

Brady_ls wrote: Wed Apr 18, 2018 9:46 pm Modem> Network Status> General Information> Modem jumps between "Sierra Wireless, Incorporated MC7455" and "no modem present."

"Does no modem present" refer to communication between the router and the card?
This is normal behavior when Connection Monitoring is enabled with Modem Reconnect, and the modem cannot stay connected to the network and/or its pings returned. When this happens, the modem is rebooted and will not be detected during the process.

Compare your logs to the image I posted earlier. Your issue also appears to be antenna/connector/signal related.
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Re: Modem Disconnecting

Post by k9kfx »

Same problem I have on sprint with the same setup. Apparently you have to have advisability perfect signal with a perfect 20 sinr to stand a chance. T-mob sim in exact same setup with worse signal and I get 2 bands 20mhz no disconnects for 2 days now. Hmmm.
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Re: Modem Disconnecting

Post by JimHelms »

Same problem I have on sprint with the same setup. Apparently you have to have advisability perfect signal with a perfect 20 sinr to stand a chance.
A perfect SINR of 20 is not required. But it must be within acceptable levels to maintain a connection.
RSRQ (dB): -14.8
SINR (dB): -2.6
RSRQ (dB): -15.6
SINR (dB): -1.6
These reading are well below acceptable levels. Compare these readings to the chart below:


Signal Readings.png

Have you tried relocating the router to a different location in an attempt to approve the signal?
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Re: Modem Disconnecting

Post by ph34rful »

Did any of you guys ever resolve this issue or at least figure out what was causing it? I'm having pretty much the same issue with a EM7455 in a USB enclosure and a Golden Orb flashed router. The blue light on the USB enclosure turns off when I experience the disconnects which I'm guessing indicates a power related issue that is most likely the result of poor signal quality, or some combination of both. Haven't really been able to make any headway on resolving the issue as the device is at a distant relative's home which makes troubleshooting very difficult, if not impossible.
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Re: Modem Disconnecting

Post by JimHelms »

ph34rful wrote: Mon Sep 03, 2018 9:25 pm Did any of you guys ever resolve this issue or at least figure out what was causing it? I'm having pretty much the same issue with a EM7455 in a USB enclosure and a Golden Orb flashed router. The blue light on the USB enclosure turns off when I experience the disconnects which I'm guessing indicates a power related issue that is most likely the result of poor signal quality, or some combination of both.
I assume you are using a quality USB power cable that attaches the USB modem enclosure to router. Using the stock cable or even a bad or faulty cable will cause disconnects. A lot of the USB power cables (including the one that come with the enclosures) will not carry the current necessary to power most higher category modems like Sierra EM7455. This possibility should not be over looked. And, it is one of the easiest fixes.

Other food for thought:

It may also help to disable Connection Monitoring until you get a stable connection. Some prefer not to run it at all.

The connection monitor pings an ip address (i.e., 8.8.8.8...) every X seconds, and if the ping fails Y number of times within Z seconds/minutes, it considers the internet connection is down and reboots the modem in an attempt to help it reconnect. This results in the enclosure's lights going off (as you mention above) while the modem reboots.

Thus, it is not hard to imagine how a modem can get stuck in an endless loop of rebooting.

If a modem struggles to maintain a connection due to inadequate signal strengths, it may be best not to use Connection Monitoring, or at least configured to be very tolerant to a number of failed pings before it decides to take action and reboot the modem--which is often a necessary step to reconnect a modem to the network.

The connection monitor's pings may prevent an idle modem (i.e., inactive, no data transferred) from being disconnected/booted from the network as an inactive device. The ping is thought to help keep the connection alive.

Also, since you are using an USB adapter enclosure behind a router, you may want to try setting Connection Monitor to Enable on Power Toggle or Modem Reconnect.

Of course, the proper functioning of any cellular modem depends on its access to adequate "usable" cellular signals.

Haven't really been able to make any headway on resolving the issue as the device is at a distant relative's home which makes troubleshooting very difficult, if not impossible.
Yes, that would make it tough.
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Re: Modem Disconnecting

Post by ph34rful »

I've indeed been wondering if it might be the USB power cable. I tried several different ones and did not notice any change, but they were at least 36". Strangely when I tested the device at my home before transferring it to my relative's there were absolutely no issues, but the signal strength is much better at my location so that's why I think it may be related. I'll probably buy the USB cable here: https://thewirelesshaven.com/shop/cables/usb-cabl ... ower-cord/
Just to rule out it being the cable. Do you happen to know if it's possible to lock the device to band 30? It seemed the drops were much less frequent on that band and it had the best speed as well. I had limited time to troubleshoot the last time I was there, but it seemed like only B2, B4, B12, B66 were supported for band lock. When I tried the command I found for B30, it seemed like I couldn't get it take/lock, but it's possible I wasn't doing it correctly. I'll have another opportunity at Thanksgiving to work on it and would like to go back with the equipment and/or knowledge needed to make it more reliable. It's been so frustrating that I've seriously considered just buying the Mofi 4500 LTE. When the current setup doesn't drop the connection and ends up on band 30 the speeds are pretty decent at 10-15mbps, but it's just so inconsistent with the many connection drops, particularly when on other bands.

Edit: Connection monitoring has always been disabled on the Golden Orb device. Also, thanks for this site! Wish it had been available when I was putting the device together in December 2017. Definitely would have made things easier, I've spent god knows how many hours trying to figure this stuff out!
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Re: Modem Disconnecting

Post by Mchccjg12 »

I've had similar issues with Sprint. My modem will disconnect pretty often, sometimes every 10 minutes, sometimes ever couple of hours. I have my MC7455 in an enclosure hooked up to a Raspberry Pi 2 B+ running Goldenorb.

EDIT: I have noticed something though, and it seems to be that most people with disconnect issues like I have seem to have a USB enclosure. I wonder if it is just a problem with the enclosure itself? Has anyone had issues with disconnects after they put the MC7455 into a router?
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Re: Modem Disconnecting

Post by JimHelms »

There is a new firmware for the MC7455 that is supposed to address some issues with Sprint. May be worth trying.
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Re: Modem Disconnecting

Post by Mchccjg12 »

I'll try that shortly and report back, I didn't notice that a new generic firmware was released. Have you updated yours to the new firmware? I would like to make sure it works just in case there are issues, as I don't have a backup of the previous firmware version to revert to.

Thank you!

PS. I'll also be trying something else to fix the power issue to see if it is that, and I will report my results on that as well!
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Re: Modem Disconnecting

Post by JimHelms »

Yes, I have used the update with no issue.

Also of interest to Sprint users is one of Sierra's notes regarding the update:

Merge Qualcomm Stack MDM9635M.LE.3.0.c2-000010218.1 to address multiple issues, including:
– MOLEMMC9X30-1117: Module crashing on Sprint network in certain locations when CA is activated"
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Re: Modem Disconnecting

Post by Mchccjg12 »

Thank you for responding! I'll be updating the firmware soon then. Also, after a peek through the release notes, I found something that I think would be a fix for it as well:
MC7455 resets periodically on Sprint network - Crash 3
Which is a fix related to RRC. Which, I had noticed, had issues on the debug for the modem. I noticed that when I turned off connection monitoring, I could look at the debug and see that the modem was still connected, with only one difference... RRC was in idle instead of connected.

Disconnected modem:

Code: Select all

Current Time:  481		Temperature: 32
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B25    		LTE bw:      5 MHz   
LTE Rx chan:   8665		LTE Tx chan: 26665
LTE CA state:  NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -74		RSRP (dBm):  -100
PCC RxD RSSI:  -69		RSRP (dBm):  -95
Tx Power:      0		TAC:         2115 (8469)
RSRQ (dB):     -10.4		Cell ID:     03E2D501 (65197313)
SINR (dB):     23.0
OK
Connected modem:

Code: Select all

Current Time:  58		Temperature: 32
Reset Counter: 2		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B25    		LTE bw:      5 MHz   
LTE Rx chan:   8665		LTE Tx chan: 26665
LTE CA state:  NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected
IMS reg state: No Srv  		
PCC RxM RSSI:  -82		RSRP (dBm):  -102
PCC RxD RSSI:  -75		RSRP (dBm):  -94
Tx Power:      0		TAC:         2115 (8469)
RSRQ (dB):     -5.7		Cell ID:     03E2D501 (65197313)
SINR (dB):     24.8
OK
From what I've read on RRC, idle means no internet connection, and it is normally a power saving feature. So hopefully this firmware should prove pretty useful in finally solving these disconnect issues!

EDIT: Seems I am still having disconnects related to RRC going Idle, even after the firmware update.
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Re: Modem Disconnecting

Post by JimHelms »

Hmm... If the RRC is related to the low power mode, then try the following commands that are related to LPM:

Code: Select all

AT!ENTERCND="A710"
AT!CUSTOM="SIMLPM",2
AT!PCOFFEN=2
AT+CFUN=1
AT!RESET
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Re: Modem Disconnecting

Post by Mchccjg12 »

Ok, seems that even after all of that, it is still disconnect, now every 5 seconds. Looking at the debug to try to figure things out, I noticed a few things.

Usually EMM state reads:
EMM state: Registered Normal Service

but before RRC does this and cuts the internet connection:
EMM state: SR Initiated ---

And then RRC reads:
RRC state: RRC Idle


So, I have no idea what is causing it, but it seems the RRC fix in the new firmware doesn't really help, even after a RMARESET.

EDIT: Apologies, seems I am dumb. I checked the version of the firmware after I did the RMARESET, and it seems that the command set the modem back to version 2.20.3, from the latest 2.30.1. So that's why it started to disconnect so much. I didn't think that the reset would revert to an older firmware version.

Though it seems even after setting the device back to the newest firmware, it still has issues... I wonder if Sprint's network just can't support it anymore.

EDIT 2: I'm at my wits end trying to solve this issue. I can't for the life of me figure out why it keeps disconnecting from the network. The ZTE Pocket Wifi works fine, so it's not an issue with the cell tower. It's something to do with the MC7455, and I can't seem to find a way to do anything about it. The weird thing is, it happens sporadically. Some days, it can be a bit better, and others, I can't go 5 minutes without it disconnecting over and over.

Also, just curious... is there any way to get the APN to stick? I read up that it might be IPV6 which is causing the issue, and using at+cgdcont to set the APN to use only IPv4 could help. However, it never seems to work, and always reverts to IPv4/v6.

Edit 3: I don't know if this matters or not, but this appeared in the system log when the modem seemed to not have an internet connection while connected to the network:
Fri Sep 28 01:17:18 2018 user.notice MBIM Monitor: Modem 1 Connection is Down (activation state: deactivated)
The way it looks, this doesn't have to do with connection monitoring.
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Re: Modem Disconnecting

Post by Mchccjg12 »

So, I called Sprint tech support to try to solve the disconnect issue with the MC7455, and take this with a grain of salt, as it's possible that it is false. But, I was told that they have made recent changes to the network to further disallow devices like the MC7455 to work. Basically, it will boot it off, even with generic firmware. It is a recent change that is apparently still rolling out, so it does at least make a bit of sense; My setup worked for a while until it suddenly stopped working, and many others had a similar thing happen to them. This doesn't bode well for those that use the MC7455 on Sprint, especially since they refused to authorize/add my device to the account as well. Though, it seems the Mofi SIM4 might still work? But I can't say for sure.
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Re: Modem Disconnecting

Post by JimHelms »

Interesting what the Sprint tech said, but I would take it with a grain of salt.

Run this command and post the return:

Code: Select all

at!entercnd="A710"
at+cgdcont?
I have seen some strange OTA APN's automatically showing up as #3 and #13.

It is not uncommon for the RRC to be idle when no data is being pulled. It could however, be in the idle state as a result of something else going on.

While your modem is in the RRC state, run these commands and see what happens:

Code: Select all

at!entercnd="A710"
AT!SCACT=1,1
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Re: Modem Disconnecting

Post by Mchccjg12 »

Sorry it took so long to reply! I've been a bit busy lately. Anyways, I have found some interesting stuff by really scrutinizing the logs. So, it seems recently the IP address started to change after the modem gets disconnected from the network... for example:

While the network is connected and working well:

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At+cgcontrdp
+CGCONTRDP: 1,5,r.ispsn,173.123.203.129,,68.28.31.30,68.28.31.31
+CGCONTRDP: 2,6,otasn,25.224.104.62,,68.28.208.215,68.28.195.150
(And yeah, the OTA APN didn't last long on the results, I got lucky to catch it when it appeared, as when I issued the command after, it only returned the first line, showing the OTA APN wasn't on the modem anymore.)

After my internet is down, but while the modem is connected to the network:

Code: Select all

At+cgcontrdp
+CGCONTRDP: 1,5,r.ispsn,173.127.112.56,,68.28.31.30,68.28.31.31
There is a difference in IP addresses, which didn't happen before from what I noticed. Also, running AT!SCACT=1,1 returns:

Code: Select all

AT!SCACT=1,1
+CME ERROR: no network service
It seems to also appear in the system log without a connection monitor, as this appears in the log when it happens:
Sat Oct 6 13:13:44 2018 user.notice MBIM Monitor: Modem 1 Connection is Down (activation state: deactivated)

So no dice there. I really do appreciate all of the help by the way!
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Re: Modem Disconnecting

Post by jstever8 »

So I have been having a very similar issue with my EM7455 (running latest Generic firmware) in an external USB enclosure connected to a Raspberry Pi 3 B+ (latest Rooter GoldenOrb firmware) running Sprint. My disconnects were happening about every 5-10 minutes or so.

I believe I have narrowed the issue down to only occurring while the modem is connected to B41. I locked the band to 25 and went an entire day without a disconnect. As of now, I have reenabled B41 and disabled CA. So far no disconnects! I have also noticed that the temperature of the modem gets quite a bit higher when B41 2xCA is active.

At first, I thought this could be a power related issue. According to the EM7455 data sheet, the highest power draw for the device would occur with B41+B41 CA as well as low signal. The power draw for the EM7455 alone is over 1A in that particular case. The Raspberry Pi is supposedly limited to 1.2A combined through it's USB bus. This led me to try a very robust power supply (capable of multiple 5V 3A outputs) with a USB Y-splitter cable to provide the additional power the device might be needing. I also upgraded the usb cable to a very short cable with a 24AWG power wire inside. Unfortunately, no dice. Still getting consistent disconnects.

Is it possible that the disconnects are related to the modem getting too hot? I am running out of ideas as to what could be the cause. I'm not convinced that Sprint is not kicking the modem off the network as I would assume it would apply to all bands and not only B41.

EDIT: It appears others are also having issues with B25 and B26, so it may not be isolated to B41 for everyone.
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Re: Modem Disconnecting

Post by JimHelms »

You may try changing the MTU value.
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Re: Modem Disconnecting

Post by swwifty »

B41 is awfully close to the 2.4ghz unlicensed spectrum. Are you by chance using 2.4ghz wifi on your Rapsberry PI? If so, try and maybe switch to 5ghz and disable 2.4ghz and see if that makes a difference.

I'm wondering if these two bands are interferering with each other, since they are so close.
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Re: Modem Disconnecting

Post by MrEdLu »

I'm new at this and am experiencing the exact same issue with loosing internet and RRC state showing RRC Idle

Has anyone resolved this yet?

My equipment
  • WE826 running GoldenOrb 2019-03-10
  • Dell Sierra Wireless DW5811E EM7455 Qualcomm WWAN NGFF Card (REV A01) 3MDGK. Flashed to Generic 02.30.01.01 with autoflash-7455.sh
  • 12v 3a power adapter
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Re: Modem Disconnecting

Post by sungpark »

Hello, I am new to the forum and did the setup rooter firmware router with em7455 on sprint network. I'm also having issues with intermittent sprint internet connection issues similar to other users having in this forum.

My setup:
- TP-link Archer C7V4 flashed with GoldenOrb 2019-03-10 firmware
- Dell Sierra Wireless DW5811E EM7455 Qualcomm WWAN NGFF Card (REV A01) 3MDGK. Flashed to Generic 02.30.01.01 with autoflash-7455.sh (exactly the same as the user 'MrEdLu')
- USB To NGFF M.2 Key B Adapter Enclosure With SIM Card Slot
- In the rooter router setup, Modem APN set to 'r.ispsn'. All other settings are default.

Two things I would like to try out to resolve the em7455 data connection issues.
- Latest sierra wilreless EM7455 generic firmware 02.30.03.00 is available. Should I upgrade the firmware? If so, what is the process? Using 'GitHub' method of automated flahsing using Ubuntu was really hard for me. If someone could post the step by step EM7455 firmware upgrade process, I would really appreciate it (but is this necessary?).
- M.2 adapter usb cable upgrade: I orderded micro usb cable with 20 awg wire, which I will try out when arrives. Some people are using powered usb cable (can someone provide me more info?). What is a better option, and will cable upgrade really help with my connection issues? FYI, sprint signal is very strong in my house.

Any help will be greately appreciated. Thank you in advance.
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Re: Modem Disconnecting

Post by JimHelms »

Can you not remove the SIM from the EM7455 enclosure, and install the Sierra Wireless software for Windows, and flash the EM7455 with generic exe firmware.

The USB micro cable that comes with the black M.2 enclosure is straight trash. And, it does cause a lot of issues related to disconnects. Your new cable may correct your problem.
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Re: Modem Disconnecting

Post by sungpark »

Jim,

Thank you for the prompt response. Regarding the EM7455 generic firmware upgrade, can I just run exe file with EM7455 enclosure connected to the windows PC? To create accessible com port for EM7455, I originally tried installing usb driver (downloaded from sierra wireless) for windows, but failed. Then I tried GitHub autoflash script from Ubuntu, which worked. I'm afraid that I might brick EM7455 installing firmware from windows. If you could provide a quick step by step installation process, I would really appreciate it.
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