LTE modem doesn’t work

I installed (as described in official documentation) LTE modem from LTE pack (QuecTel ET20 - never been used before) on USB3 to new Turris Omnia. After installation it worked till first reboot. From this time I was successful two or three times to get connection (T-Mobile CZ) to the internet, but don’t know why.
After factory reset it worked again till first reboot.
Any idea what happened? It doesn’t look like HE issue.
Thanx in advance.

Welcome to the Lte problems club.
After many years of experience with TO Lte, here is my advise if you wish to keep this buggy modem.

  1. Ask cz.nic team to provide newer firmware for the modem. @Pepe Quectel does not respond back to emails for newer firmware, could cz.nic team ask for it?
  2. Use qmi cellular to set the interface rather than what is described in official documentation
  3. Set your modem to use only LTE or 3g or gsm and look at the signal:
    To set lte only use the command below:
    uqmi -d /dev/cdc-wdm0 --set-network-modes lte
    To see the signal quality the command is:
    uqmi -d /dev/cdc-wdm0 --get-signal-info
    Based on your tests, select the best signal LTE or 3g (or even gsm if you need stability)
  4. Install watchcat and set it up to reboot the router if there is no internet (though this might not work most of the times)
  5. Install usbreset, find your usb modem (something like Bus 001 Device 002: ID 05xx:92xx Qualcomm, Inc. Acer Gobi 2000 Wireless Modem ) using lsusb and issue:
    usbreset 05xx:92xx when the modem hangs.
  6. In the unlike case that usbreset does not do the job your final two options are:
    6.1 Use AT command to reset it: echo -e "AT+CFUN=1,1" > /dev/ttyUSB2
    6.2 Power cycle the router

since version 0.99 I have had some minor problems with lte. I wrote various correction scripts to solve the problems. Your problem after restarting the modem was one of several. This problem I fixed with ifdown and ifup interface of LTE after modem reboot. But after the last fw I did a factory reset. I did All setings again and all problems with the LTE disappeared even without correction scripts. Sure I don’t know what is diferent about LTE from old versions to new. But problems wit LTE are individual and I made repairs individually for different devices and situations. Examples AT commands for reset was not working everytime.