What am I doing wrong with AT&T?

[JohnnyDaMitch]

I have the AT&T Business Unlimited Elite plan. The signal is not strong, so for usable speeds (ie, faster than the 4 or 5 megabit I can get with DSL) I have to use a directional antenna, which rules out any sort of phone or tablet tethering.

Currently, the modem I'm using is Sierra Wireless EM7565, flashed with the AT&T specific firmware (I did that a while back and it seemed to resolve issues with getting connected). I also have a Quectel EM12 available. The router is a PC running Ubuntu 21.04. I set up hostapd and bridged the wifi and lan together, so that I can use it just like a regular wifi router. The modem is installed in a USB 3 M.2 enclosure. I use dnsmasq for DNS and DHCP on the LAN.

I've found that I get a CallFailed error unless I use 'Broadband' as the APN. Will this mean that all my data counts against the hotspot limit? I figure I could have problems there, down the line.

But at the moment, the issue I'm seeing is that I can start up a ping to some internet host, then physically plug in the LAN connection to the rest of my network, and within seconds those ICMP packets are blocked. All traffic appears to be blocked until I do a modem reset. Using the iptables mangle command to set TTL to a value of 65 makes no difference.

I tried setting up wireguard, using my AWS host as the endpoint, and it works, but for some reason the connection becomes extraordinarily slow. Like, 5 seconds to send a ping (though the reported round trip time is only 200ms or so - what's that about?). There's advice out there online about MTU settings and TCP MSS clamping - doesn't seem to help me.

I could really use some advice from an expert. My only remaining idea is to look into IMEI spoofing, but that seems dangerous.

[MattB29]

I am not an expert. However it sounds like either your signal strength is poor (you are getting LTE?)or you are being throttled due to using up your hotspot data allotment.

[gscheb]

Don't have any experience with this plan.
Do have experience with AT&T tablet plan.
There had been an issue where the apn was wrong. Was set to NXTGENPHONE or something instead of broadband. Now when this happened it still worked but only on 3G. Soon as it was changed to broadband speeds returned to 4G LTE.

[Dr-BroadBand]

Signal + SIM = Data

MattB29 hit the nail on the head.

Sounds crazy but.
The easiest way do you get great signal, just bring your gear to the tower for a speed test.

If that doesn’t fix your problem it’s your SIM

[MattB29]

One other thing comes to my mind about Ubuntu. I read somewhere that crazy long ping times when using a cellular modem through Ubuntu. You might do some searching to see if something pops up. Perhaps over on the Ubuntu forum you can ask. That is if the problems is not with your connection to AT&T.

[JohnnyDaMitch]

To clarify, the main issue I have is that the connection cuts out completely as soon as there's more than one device communicating on the network. This doesn't depend on signal strength.

What should I try to fix this?

edited to add: I've seen the exact same thing occur with another SIM, an individual AT&T account that's signed up to the data-only plan.

[Dr-BroadBand]

Sounds like a new router may be needed.
Would talk with the boys at the The Wireless Haven Store.

[mtl26637]

I too have an EM7565 and I don't recall changing the firmware to specific provider. I've had several setups and I've never had to use 'carrier' firmware. I would first try going to the generic firmware. Second thing is your APN. Find out what the exact APN is for that plan and use it with the generic firmware and hopefully you will be good to go. The 'nxtgenphone' is apn for phones, 'broadband' seems to be the catch-all apn and for tablets. I doubt that broadband is the correct apn for a business plan. Also, apn settings directly affect pings since your apn is basically which gateway/route to take once you make it to the tower.

Watch the logs of the 'AT' commands after a reboot of the modem and see if you can catch what apn settings are already programmed into the sim. The sim may already be set to the correct apn and no need to actually set the apn manually.

[JohnnyDaMitch]

I too have an EM7565 and I don't recall changing the firmware to specific provider. I've had several setups and I've never had to use 'carrier' firmware. I would first try going to the generic firmware.

I had tried going back to the generic firmware and although that seemed like it didn't work at the time, I remembered that when I flashed the carrier firmware back afterwards, it had taken forever before I got the connection to come up again. So I tried it again, and gave plenty of time for the network to "adjust," or whatever. It started working with the generic firmware. I think it takes like 15 minutes, at least. So, yes! Thank you.

Second thing is your APN. Find out what the exact APN is for that plan and use it with the generic firmware and hopefully you will be good to go. The 'nxtgenphone' is apn for phones, 'broadband' seems to be the catch-all apn and for tablets. I doubt that broadband is the correct apn for a business plan.

Now on the generic firmware, I'm still seeing a failure to start up the connection when I try NXTGENPHONE. I have verified that this was the APN when the SIM was initially in my phone (at that time, I had a dummy IMEI programmed by the local AT&T person, and it worked in my phone but not in the modem. my understanding is that currently my modem IMEI is set on the account even though it's a phone plan. they described it as a "workaround" to get it going, and I just played dumb.)

Here's the log for that connection failure. Initially it went through some somewhat different looking messages. Now it fails right away, with these messages:

Code: Select all

May 26 17:55:05 -wan NetworkManager[1001]: <info>  [1622069705.4003] policy: auto-activating connection 'AT&T connection' (1b5b67bd-4b31-421b-b89b-676c21632a32)
May 26 17:55:05 -wan NetworkManager[1001]: <info>  [1622069705.4006] device (cdc-wdm0): Activation: starting connection 'AT&T connection' (1b5b67bd-4b31-421b-b89b-676c21632a32)
May 26 17:55:05 -wan NetworkManager[1001]: <info>  [1622069705.4007] device (cdc-wdm0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
May 26 17:55:05 -wan NetworkManager[1001]: <info>  [1622069705.4013] manager: NetworkManager state is now CONNECTING
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] simple connect started...
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] simple connect state (4/8): wait to get fully enabled
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] simple connect state (5/8): register
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] simple connect state (6/8): bearer
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] simple connect state (7/8): connect
May 26 17:55:05 -wan ModemManager[1090]: <info>  [modem0] state changed (enabled -> connecting)
May 26 17:55:05 -wan NetworkManager[1001]: <info>  [1622069705.4196] modem["cdc-wdm0"]: modem state changed, 'enabled' --> 'connecting' (reason: user-requested)
May 26 17:55:21 -wan ModemManager[1090]: <warn>  [modem0] couldn't load operator code: Current operator MCC/MNC is still unknown
May 26 17:55:21 -wan ModemManager[1090]: <warn>  [modem0] couldn't load operator name: Current operator description is still unknown
May 26 17:55:35 -wan ModemManager[1090]: <info>  [modem0/bearer1] couldn't start network: QMI protocol error (14): 'CallFailed'
May 26 17:55:35 -wan ModemManager[1090]: <info>  [modem0/bearer1] call end reason (1018): gsm-wcdma-option-unsubscribed
May 26 17:55:35 -wan ModemManager[1090]: <info>  [modem0/bearer1] verbose call end reason (6,33): [3gpp] option-unsubscribed
May 26 17:55:35 -wan ModemManager[1090]: <warn>  [modem0/bearer1] connection attempt #8 failed: QMI protocol error (14): 'CallFailed'
May 26 17:55:35 -wan ModemManager[1090]: <info>  [modem0] state changed (connecting -> enabled)
May 26 17:55:35 -wan ModemManager[1090]: <info>  [modem0/bearer1] connection #8 finished: duration 0s, tx: 0 bytes, rx :0 bytes
May 26 17:55:35 -wan NetworkManager[1001]: <info>  [1622069735.7811] modem["cdc-wdm0"]: modem state changed, 'connecting' --> 'enabled' (reason: user-requested)
May 26 17:55:35 -wan NetworkManager[1001]: <warn>  [1622069735.7817] modem-broadband[cdc-wdm0]: failed to connect modem: QMI protocol error (14): 'CallFailed'
May 26 17:55:35 -wan NetworkManager[1001]: <info>  [1622069735.7818] device (cdc-wdm0): state change: prepare -> failed (reason 'unknown', sys-iface-state: 'managed')
May 26 17:55:35 -wan NetworkManager[1001]: <info>  [1622069735.7827] manager: NetworkManager state is now DISCONNECTED
May 26 17:55:35 -wan NetworkManager[1001]: <warn>  [1622069735.7846] device (cdc-wdm0): Activation: failed for connection 'AT&T connection'
May 26 17:55:35 -wan NetworkManager[1001]: <info>  [1622069735.7848] device (cdc-wdm0): state change: failed -> disconnected (reason 'none', sys-iface-state: 'managed')

The 'reason: option-unsubscribed' part is interesting. That specific message is new. Before it said CallFailed and I think an unknown reason.

To also respond to the suggestions from others (thanks to all!)- I did speak with a guy at The Wireless Haven and found out that as far as they're aware there's not anything built-in to those firmwares that does the IP masquerading differently, or something like that to explain the failure to hide our having a whole LAN with multiple clients on it.

However, I also went ahead and ordered the WG3526-P from The Wireless Haven, as this was the router recommended when we had that conversation. And I want to reduce any differences between how I'm going about this and how others do. So we'll see if it makes any difference.

Any other thoughts? This looks to me like they're doing IP fingerprinting of some sort. Perhaps with TCP sequence numbers or something, or maybe known hosts that are OS-specific. But could it be, that i'm the first to observe it and then report back here?

[Dr-BroadBand]

Sounds like you will soon have a killer setup way to go!!

[mtl26637]

I'm not familiar with your router side of the setup which uses different software than what most use here at this site. Maybe someone that is familiar with "Modemmanager" will chime in. May have to wait till you get your The Wireless Haven router and see what results you get. I'm very surprised that a "business" account uses the nxtgenphone apn? I always thought the business accounts had used a different apn but not positive on that. You may try to verify the apn with a diffent att rep just to make sure? If all else fails you might find that your account is tied to that original IMEI.

[Didneywhorl]

You may want to try working over a VPN to see if the network is managing you and seeing multiple devices. A simple proxy may work too. ATT is tricky sometimes. Voice plans especially. Everyone that I know using the Business Elite Voice plans are also changing the modems identity to a phone.

[JohnnyDaMitch]

Thanks for that info. It may be what I'll have to do. I haven't yet researched those techniques.

The WG3526 arrived today. It doesn't work with the modem connected via USB- no modem device is detected. So I'm now waiting again, this time for a miniPCI to m.2 adapter so that I can install it internally.

I'm pretty certain there was nothing wrong with my Ubuntu setup, or put another way, nothing special about Goldenorb and/or WiFix. At least this looks like nice, dependable hardware that might be less likely to get bugs in it (literal bugs).

[Didneywhorl]

I like the WG3526-P with the modem installed inside, it removes un-needed failure points.

[cagordon1985]

Try every band one at a time when all else fails. I tried to follow the general known bands in my area, and everything is backwards. ATT on Tmobile bands, Tmobile on ATT bands, Verizon using ATT first responders band. WTH

[Adm1jtg]

I also have a wg3526 and have used it BOTH with a usb to pcie adaptor (externally) and internal card slot. Use the wifix firmware (its a modified version of goldenorb). Mine is dated 5/16/2020 though I have the NON poe version and am not sure if the firmware will differ for your version.

As far as bands I would try 2,4,5 and 12 to start with those are what is TYPICALLY used. Also this sounds silly but be sure the tower your pointing at is an att or att supported tower. For example in my area there are towers that are very strong that use 2,4,5 for BOTH att and verizon but if your att your not allowed to use the verizon tower and vice versa.

Lastly as far as them perhaps packet sniffing and thats why its not allowing your second device there is an easy way around that. I cannot tell you how as thats illegal in this forum but you can change your imei of the modem card and the ttl to make your modem card look like a generic phone on your account. A previously phone registered to the account that you no longer use would be optimal. This will stop any filtering and such as all traffic will appear to be just simple traffic from whatever device you used the imei from.

To be clear I am recommending this as a TEST, if you choose to use it beyond that its on you as technically this is illegal.

[toddw]

I would also see if Band29 is active, it just started popping here for ATT and its helped quite a bit with CA.

[Didneywhorl]

I would also see if Band29 is active, it just started popping here for ATT and its helped quite a bit with CA.

Interesting

[JohnnyDaMitch]

The USB port simply did not work. I don't know what that was about, but I received the mini-pcie adapter yesterday, so problem solved. Luckily, I already had the MHF4 version of the antenna pigtail connectors, although one of them was too short, so I had to do some rearranging of the antenna ports. I have switched to the Quectel EM12-G modem.

As I suspected, the situation was initially the same as with the Ubuntu box.

Everyone that I know using the Business Elite Voice plans are also changing the modems identity to a phone.

This is the key thing. Here are my tips, now that I have it working:

• Use a phone plan. I picked the most expensive one on a business account, in the hopes that it has the least deprioritization.

• Use the APN that's for phones. That would be NXTGENPHONE for me, but you'll want to confirm it's correct for the plan you have. Broadband is not the one.

• Use a Quectel modem.

• Use a phone IMEI, and then don't ever use that phone on any cellular network again. This forum is not the place to find out how to do this step. With Quectel, it is not hard.

• Set your custom DNS to something that's not AT&T. I used the Google one, 8.8.8.8 and 8.8.4.4. This was the final piece of the puzzle that got it working.

• AT&T does not require TTL hacks at this time.

I do have one more question. What's all the talk about manually selecting a band? How might this help me? Right now I'm on B12.

[gscheb]

Hello

This is about Quectel band selection

https://wirelessjoint.com/viewtopic.php?f=16&t=943

[Adm1jtg]

Sometime the default band the router chooses is not the optimal band. In my own situtation I am a verizon user and I have the following bands available:
2,4,5,13,66
for me 2 and 13 are absolute garbage. Meaning either poor quality or porr signal strength. % is the best balance of strength and quality overall but my router wouldnt always pick 5 as the band to use. There is an at command spreadsheet on here somewhere so that you can issue an AT command to tell your router to ONLY use specific bands, thereby skipping or excluding the bands known to perform less well.

I cant find the spreadsheet but will copy paste from a forum post I have bookmarked on how you can do this manually.

While it doesnt state it in the text below I have found I need to reboot the router after issueing the commands:

Enter the following AT commands, and write down your original band values before changing anything.

AT+QNWINFO < Current band in use
AT+QCFG=”Band” < Current bands config
AT+CSQ < Check signal strength


To configure single LTE bands or combinations, use the following AT Commands:

Band# - AT Command
2
AT+QCFG="band",0,2,1
4
AT+QCFG="band",0,8,1
5
AT+QCFG="band",0,10,1
2+4
AT+QCFG="band",0,a,1
2+4+5
AT+QCFG="band",0,1a,1
12
AT+QCFG="band",0,800,1
2+4+12
AT+QCFG="band",0,80a,1
2+4+5+12
AT+QCFG="band",0,81a,1
2+12
AT+QCFG="band",0,802,1
4+12
AT+QCFG="band",0,808,1
5+12
AT+QCFG="band",0,810,1

All bands:
AT+QCFG="band",0,42000000003300185a,1

All bands for the EP06-E specifically:
AT+QCFG="band",8d0,1a1880800d5,0

Or use the default value you have written down earlier for your particular modem.
On some modems you have to use this command format:
AT+QCFG="band",2e0,<band_value>,0

Band_value - Band#
1 - LTE BC1
2 - LTE BC2
4 - LTE BC3
8 - LTE BC4
10 - LTE BC5
20 - LTE BC6
40 - LTE BC7
80 - LTE BC8
100 - LTE BC9
200 - LTE BC10
400 - LTE BC11
800 - LTE BC12
1000 - LTE BC13
2000 - LTE BC14
10000 - LTE BC17
20000 - LTE BC18
40000 - LTE BC19
80000 - LTE BC20
100000 - LTE BC21
1000000 - LTE BC25
2000000 - LTE BC26
8000000 - LTE BC28
100000000 - LTE BC33
200000000 - LTE BC34
400000000 - LTE BC35
800000000 - LTE BC36
1000000000 - LTE BC37
2000000000 - LTE BC38
4000000000 - LTE BC39
8000000000 - LTE BC40
10000000000 - LTE BC41
20000000000 - LTE BC42
40000000000 - LTE BC43
20000000000000000 - LTE BC66
400000000000000000 - LTE BC71

For specific band combinations, simply add the hex values together using a hex calculator.
For example: Band 2 (2) + Band 12 (800), therefore the summ in (x) = 802
Or use a band calculator posted in the forum.
These changes take affect without requiring a reset or reboot.
You will have to wait about 5-10 seconds for the switch to occur.

[JohnnyDaMitch]

I appreciate those answers. Thanks!