While developing scripts for Mikrotik CME22 using the BG77 module, we have a few devices that becomes tired in the sense that communication via port 80 (web) is nearly impossible except for the login screen. Ping test for equal modems at the same spot shows equal response times. All modems have same level of software and firmware at+gmr: BG77LAR02A04. LTE-M Signal strength is good and equal. So everything is equal but not the port 80 access.
The modems that suddenly becomes tired were good when set up the first times.
Any idea why some of these modems becomes tired ?
After additional investigation on the LTE connection, it seems that our routers choose different providers as the SIM card provider try to establish at the fisrt time connection.
The faulty routers connect to a different provider compared to all the well working routers. So now the questions is:
How do I reset the BG77 to initiate search for a new provider ?
or
Do the BG77 keep information about the last connection after a power reset ?
Are the “new provider” you described referring to the local “carrier”?
Yes, BG77 usually retains the EARFCN of the last connected base station cell as well as the network standard.
The providers we use at this loaction shares the samme antennas (23802, Telenor and 23820 Telia/norlys). By use of the AT+COPS command i changed from 23802 to 23820, and suddenly the modem worked well. Turning back to 23802 it stil works well - strange. Both testet for LTEM and NBioT.
Thank you for the tip that the modem retain the last provider information.
By great help from the provider giving trouble, the solutions to get it up and running was the MTU settings. We had the MTU set to 1420, which is standard for Wireguard. By lowering MTU to 1380 everything runs very well.
Our SIM card provider confirmed that this is a known issue, but hard to trace.