Frequent modem disconnects MC7455/WG3526

[Vegas]

The modem drops connection frequently, seems to correspond with a new or returning device accessing wifi. Other wifi devices can still communicate to the router, but no internet service. I setup connection monitoring with modem reconnect which brings it back up very quickly.

I've already reset and reconfigured the modem to MBIM and added the Sprint OTA. No change. Using Calyx Sprint SIM.

Any ideas?

[JimHelms]

What does your signal stats look like while connected. It is possible that the signals are less than optimal, and it is connecting on Band 41 at 2500HMz and the 2.4GHz (2400MHz) may be interfering and/or interrupting the quality of signals being received by the modem.

Also, try disabling Connection Monitor.

While it is connected, run the following command and post the results:

Code: Select all

AT!GSTATUS?

[Vegas]

Without connection monitoring, it does the same thing but requires intervention to reconnect... resetting the router or modem.

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  30790		Temperature: 50
Reset Counter: 12		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B41    		LTE bw:      20 MHz  
LTE Rx chan:   41292		LTE Tx chan: 41292
LTE CA state:  ACTIVE      		LTE Scell band:B41    
LTE Scell bw:20 MHz  		LTE Scell chan:41490
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		

PCC RxM RSSI:  -62		RSRP (dBm):  -92
PCC RxD RSSI:  -71		RSRP (dBm):  -97
SCC RxM RSSI:  -68		RSRP (dBm):  -98
SCC RxD RSSI:  -66		RSRP (dBm):  -92
Tx Power:      5		TAC:         012B (299)
RSRQ (dB):     -6.5		Cell ID:     0034A43A (3449914)
SINR (dB):     25.6


OK

[JimHelms]

Your antenna stats are usable.

Your issue could be related to the MTU value being too large for the tower you are using. This seems to affect some and not others.

This are recent discussions on the GoldenOrb Forum concerning this type of Sprint connection issues. Start on the bottom page and read forward.

[Vegas]

I changed to n.ispsn and set the MTU value to the one suggested in the forum... still disconnecting. I'll see if disabling the wifi and setting up another router as an AP will be smoother.

It's definitely workable... it reconnects so quickly it doesn't even stop video streaming. Every once in awhile I'll notice a website take too long to load and I know it's resetting, and see it in the logs, but I can live with that. I just wish I could pin point the cause.

[JimHelms]

What did you finally use for the MTU value? You might also try 1428.

[Vegas]

1484. I'll try 1428

[JamesReinhold]

Jumping in to add another suggestion on this thread. I've built 2 MC7455/WG3526 setups and one has had very good performance. The other was good for a while and then also started having what appeared to be frequent disconnects, but where actually reboots. This was happening anytime the router/modem was being used (traffic) or multiple devices connecting. I isolated the router and modem card - which worked fine independently. Going off a hunch I swapped power adapters between the two WG3526's and right away noticed they were different.

This is the power adapter for the WG3526 that was rebooting under traffic load:

20190925_065229.jpg

And this is the power adapter for the WG3526 that is working fine:

20190925_165707.jpg

Now - not sure why these are different, but both are what came with the WG3526 and they have quite different outputs.

So may want to check power supply when running into reboot type issues.

[BillA]

Jumping in to add another suggestion on this thread. I've built 2 MC7455/WG3526 setups and one has had very good performance. The other was good for a while and then also started having what appeared to be frequent disconnects, but where actually reboots. This was happening anytime the router/modem was being used (traffic) or multiple devices connecting. I isolated the router and modem card - which worked fine independently. Going off a hunch I swapped power adapters between the two WG3526's and right away noticed they were different.

Now - not sure why these are different, but both are what came with the WG3526 and they have quite different outputs.

So may want to check power supply when running into reboot type issues.

Well, no wonder, the top adapter is a 0.75Amp at 8Volts (which equals to only 0.50Amp at 12Volts), while the bottom one is much beefier 2.5Amp at 12Volts, in other words the top one is really low, thus the frequent disconnects. By the way, you can't really trust the labels either, I've come across labels showing 2Amp at 12Volts which turned out more like 1Amp even under a light load. I've learned over decades of troubleshooting electronics, that most issues turn out to be simpler than thought, yet we keep digging in all the wrong places.

[ruralbee]

I'm getting the exact same behavior on EM7565. I'm on Sprint as well with r.ispsn. I upgraded from the MC7455 to the EM7565 hoping to fix the connection drops. It goes faster but drops just as much, if not more, & is mainly noticeable under load. I have upgraded the USB cable, tried it with connection monitoring, without, varying the settings, etc... Not much improvement. MBIM or QMI doesn't seem to make much of a difference.

I'm using a Linksys WRT1900ACS with the USB enclosure w/ a 3A stock power supply. External omni antennas about 4 miles from Sprint, nearly LOS.

I'll let you know if I figure out a solution. It feels like it is a USB issue but I can't confirm that. I had narrowed the system & kernel log down but I have no idea what it means.

my logs are attached for reference & comparison

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  2240		Temperature: 35
Reset Counter: 51		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B41    		LTE bw:      20 MHz  
LTE Rx chan:   41094		LTE Tx chan: 41094
LTE SSC1 state:INACTIVE    	LTE SSC1 band: B40    
LTE SSC1 bw  : 20 MHz  		LTE SSC1 chan: 41292
LTE SSC2 state:INACTIVE    	LTE SSC2 band: B40    
LTE SSC2 bw  : 20 MHz  		LTE SSC2 chan: 41490
LTE SSC3 state:NOT ASSIGNED
LTE SSC4 state:NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		

PCC RxM RSSI:  -63		PCC RxM RSRP:  -96
PCC RxD RSSI:  -63		PCC RxD RSRP:  -91
SCC1 RxM RSSI: -76		SCC1 RxM RSRP: -97
SCC1 RxD RSSI: -72		SCC1 RxD RSRP: -89
SCC2 RxM RSSI: -82		SCC2 RxM RSRP: -99
SCC2 RxD RSSI: -75		SCC2 RxD RSRP: -91
Tx Power:      --		TAC:         1e20 (7712)
RSRQ (dB):     -10.0		Cell ID:     03d55f32 (64315186)
SINR (dB):      5.4


OK

[JimHelms]

I'm using a Linksys WRT1900ACS with the USB enclosure w/ a 3A stock power supply. External omni antennas about 4 miles from Sprint, nearly LOS.

I'll let you know if I figure out a solution. It feels like it is a USB issue but I can't confirm that. I had narrowed the system & kernel log down but I have no idea what it means.

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  2240		Temperature: 35
Reset Counter: 51		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B41    		LTE bw:      20 MHz  
LTE Rx chan:   41094		LTE Tx chan: 41094
LTE SSC1 state:INACTIVE    	LTE SSC1 band: B40    
LTE SSC1 bw  : 20 MHz  		LTE SSC1 chan: 41292
LTE SSC2 state:INACTIVE    	LTE SSC2 band: B40    
LTE SSC2 bw  : 20 MHz  		LTE SSC2 chan: 41490
LTE SSC3 state:NOT ASSIGNED
LTE SSC4 state:NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		

PCC RxM RSSI:  -63		PCC RxM RSRP:  -96
PCC RxD RSSI:  -63		PCC RxD RSRP:  -91
SCC1 RxM RSSI: -76		SCC1 RxM RSRP: -97
SCC1 RxD RSSI: -72		SCC1 RxD RSRP: -89
SCC2 RxM RSSI: -82		SCC2 RxM RSRP: -99
SCC2 RxD RSSI: -75		SCC2 RxD RSRP: -91
Tx Power:      --		TAC:         1e20 (7712)
RSRQ (dB):     -10.0		Cell ID:     03d55f32 (64315186)
SINR (dB):      5.4


OK

Sprint and the EM7565 usually play very well together. Thus, your antennas stats look good.

The first thing I would try is to disable connection monitor. I have seen this cause issues with various builds and modems.

Power issues will cause disconnects, especially when the modem is under load--which it can pull up to an amp of power.

What type of USB to M.2 enclosure are you using?

[Didneywhorl]

Good quality usb cord replacement may be suspect as well

[ruralbee]

Thanks for the suggestions... I have disabled connection monitoring. It can definitely adversely affect things with certain settings. I just had it on monitoring only & that was causing a lot of instability under load, which is interesting. It got so bad, I changed it back to switching between power toggle / modem reconnect.

As for the enclosure I'm using ... I'm using the The Wireless Haven one... https://thewirelesshaven.com/shop/pcie-m-2/mini-p ... card-slot/

And I did upgrade the stock USB cord to one I found on Amazon, 3 times the thickness made by Tripp Lite ... Tripp Lite U326-003 USB 3.0 Super Speed 5Gbps. Appears to be of good quality.

[Didneywhorl]

Did you try to connect the enclosure directly to a pc, eliminating any wierdness with your router? I doubt itll be different since it provides a different load on the unit, but still.

[JimHelms]

We have really not heard of an under powered issue with the USB3 cables that come with the M.2 adapter enclosure.

You may want to use a USB digital voltage meter to check the USB port voltage/amps on the WRT1900ACS. It is possible it is not providing enough juice to the adapter.

One other way you could test this is to use a USB3.0 power hub if you have one available.

Or, you may want to try something like THIS and combine the USB ports.

[BillA]

Thanks for the suggestions... I have disabled connection monitoring. It can definitely adversely affect things with certain settings. I just had it on monitoring only & that was causing a lot of instability under load, which is interesting. It got so bad, I changed it back to switching between power toggle / modem reconnect.

As for the enclosure I'm using ... I'm using the The Wireless Haven one... https://thewirelesshaven.com/shop/pcie-m-2/mini-p ... card-slot/

And I did upgrade the stock USB cord to one I found on Amazon, 3 times the thickness made by Tripp Lite ... Tripp Lite U326-003 USB 3.0 Super Speed 5Gbps. Appears to be of good quality.

On the USB3.0 To Mini PCI-E Adapter Enclosure besides the regular usb connector which you plug into your router or pc, there's also a secondary micro usb power port you could use to supply additional power. Those two used together should provide enough current to eliminate any reboots.

[ruralbee]

I’ll give those suggestions a shot and report back. Thank God for Amazon’s next day delivery

[ruralbee]

Regarding the EM7565, the USB voltage meter arrived today. I put the system under load & got a few pics, which are below. The Y connector arrives tomorrow.

Twice it seemed to become unstable the longer the meter is inline and started dropping connections very frequently, Third time, the connection was solid for awhile (30 mins). Unpredictable somewhat.

I also was perusing Sierra Wireless forum & the command reference guide and ran across two related commands, which return the following values

I'm not 100% certain how to interpret any of this. At roughly the same instantaneous time, the meter is showing nearly 4.91 - 5.02 V, whereas the modem is reporting back 3.3 V, even under load.

The wild card is the amps & if that plays a factor. The meter is showing under load it is hitting 0.320 A and ranges down to 0.123 & 0.240 A. It varies constantly based on the modem's demand.

Or perhaps the voltage is too high & it is tripping the modem.

at!pcvolt?
Volt state: Normal
Power supply voltage: 3392 mV (ADC: 9880)


AT!PCVOLTLIMITS?
HI CRIT: 4600
HI WARN: 4400
HI NORM: 3300
LO NORM: 3135
LO CRIT: 2900

Thoughts / ideas appreciated.

Lane

usb5.jpg

usb2.jpg

[BillA]

Regarding the EM7565, the USB voltage meter arrived today. I put the system under load & got a few pics, which are below. The Y connector arrives tomorrow.

Twice it seemed to become unstable the longer the meter is inline and started dropping connections very frequently, Third time, the connection was solid for awhile (30 mins). Unpredictable somewhat.

I also was perusing Sierra Wireless forum & the command reference guide and ran across two related commands, which return the following values

I'm not 100% certain how to interpret any of this. At roughly the same instantaneous time, the meter is showing nearly 4.91 - 5.02 V, whereas the modem is reporting back 3.3 V, even under load.

The wild card is the amps & if that plays a factor. The meter is showing under load it is hitting 0.320 A and ranges down to 0.123 & 0.240 A. It varies constantly based on the modem's demand.

Or perhaps the voltage is too high & it is tripping the modem.

It's normal for the voltage at the router's power input jack to be higher than 5V, there's a power regulator inside. I've read in the specs that it can usually handle anything between 5 to 12Volts. The modem's 3.3V is also normal, probably running on a 3.3V chipset. It would be more important to measure the power rail after the voltage regulator with test probes, which feeds all the various circuits. You'll just have to poke around (do not short it out!) the 3 pins of the LM78xx regulator, or around the Buck converter's output large filters caps (near the black square/round ferrite coil, but not sure which type of regulator you have in your particular router).
The most important thing is that the voltage doesn't fall below 5V at the power input jack. If it does, that means that the amperage is simply too low to handle the load spikes. You can try a beefier 5-10V@3-4Amp replacement adapter. As long it's a high quality power adapter, yet it's still rebooting, then you may have some fault on the main board and/or modem.

[JimHelms]

You may find these of interest. They are taken from the EM7565 Product Technical Specifications.

You will note that CA requires a lot more power to the modem than one would suspect.

EM7565 DC Power Consumption.png

EM7565 Power Consumption 2.png

[ruralbee]

Thanks for the charts Jim. Very informative & surprising. The Y USB 3.0 cable arrived this afternoon. After I connected it, I haven't really had any noticeable drops.

Interestingly, about 30 min after I hooked it up, Sprint took down the main tower we are on. The modem struggled for about an hour with a tower fairly far away, but finally locked onto another tower somewhat closer. It is holding steady so far, albeit a bit slower on the download. The The Wireless Haven omni antennas https://thewirelesshaven.com/shop/antennas/4g-lte ... l-antenna/ saved me from a bit hassle. Next project is to switch to yagis, once the LOS tower is back up.

Hopefully the extra power will solve the drops and others facing this issue!

Thanks for all the support

Lane

[ruralbee]

A brief follow-up. It appears the disconnect issues I was facing with Sprint & the EM7565 were indeed related to inadequate amps reaching the modem inside the M2 enclosure. For context, the Linksys WRT1900ACS has a 3A / 12 v supply but the output of the USB port itself was inadequate. After adding the Y USB configuration that Jim suggested, it provided additional amps to the modem by combining the output from USB 3.0 & 2.0 ports. Since adding that cord, the modem log has zero disconnects other than the daily auto-restart I have scheduled early each morning. It has been stable over a week now. I may try reverting it back to QMI mode to see if the stability persists. Currently in MBIM mode. You kind of hate to touch anything when it is working, more or less, flawlessly.

thanks everyone,

Lane

[JimHelms]

It has been stable over a week now. I may try reverting it back to QMI mode to see if the stability persists. Currently in MBIM mode. You kind of hate to touch anything when it is working, more or less, flawlessly.

Thanks for the update. There is a lot to be said of the old adage, that if it not broke, why fix it.

[castrocomp]

Where in the software do I go to change the MTU setting?

[Didneywhorl]

Where in the software do I go to change the MTU setting?

Network-> Interfaces-> [whichever is your modem/wwan0 interface, mine is WAN1] -> Edit -> Advanced Settings -> Override MTU