TRB141 mysterious internet outages

[company_man]

I have had issues with TRB141 units mysteriously losing their internet connection via 4G.

The cellular connection still works, because the devices still receive SMS.

Lately I have had different TRB141 devices running firmware 07.18.2 lose their internet connection, only to regain it later. Outages have lasted between 2 hours and 48 hours. One is currently ongoing.

To try to find out what is happening, I installed 5 units in my office and just left them running. Today, after having run for a few days, they all go offline at about the same time, 00:45 November 19, UTC. (edit: also note, we have others running elsewhere that are still going fine and did not go offline, all configured exactly the same…)

I rebooted one, and it began working again.

On another unit, I tried restarting the cell connection without rebooting, but still no internet access. I can’t ping 1.1.1.1 or 8.8.8.8, I can’t access any DNS, or otherwise get anything from the internet.

I have made backups of the troubleshoot files from 3 of the units during the outage – I will leave them powered on, if the internet comes back as in previous outages, I will get more troubleshoot files from them that may help explain something.

I’ve also taken a photo of the LEDs showing the cell connection is OK (and noting that they can still receive SMS).

I would REALLY like to resolve this because multi-hour outages will cost us a lot of business, and I want to keep buying Teltonika hardware if we can make it work.

If I can do anything to help debug this please let me know, I have left a few units running with the problem in case that helps.

Thanks

[company_man]

Update: one stopgap solution is gsmctl -Q to reboot the modem.

Restarting the connection only from the WebUI does not work. gsmctl -Q does work, but I do not know why.

I would still like to know why this happens and whether there’s a better way to resolve the problem?

I don’t consider a stopgap a “solution” so I won’t mark this solved until we at least identify the cause.

I vaguely suspect this has something to do with DHCP lease from the carrier, but I’m not sure because I’m not a networking expert. It would explain the random outage duration (depending on how far into the DHCP lease the outage began) right? And the max outage length being a couple of days…

[Matas]

Hello,

@company_man

vaguely suspect this has something to do with the DHCP lease from the carrier,

I was actually thinking this as well, purely due to the fact that you mentioned all of these devices losing connection pretty much at the same time. Device reboot/Modem restart pretty much re-news this lease, which, in result, restores the connection.

A few suggestions I’d have for you to test out:

1. If you wish, you could upgrade one of the firmwares for your TRB to 7.19.1 to see if the result imrpoves: TRB141 Firmware Downloads - Teltonika Networks Wiki
2. Head to your WebUI → System → Maintenance → Auto-reboot and set up a rule under the Ping/Wget section that would look like the following:
   
   

Regards,
M.