RM520N-GL – LTE Registration Loss / Radio Stack Stuck Issue

IoT Modules 5G Module
,
1

We are using the Quectel RM520N-GL (Firmware: RM520NGLAAR01A07M4G) in an OpenWrt 24.10.4 environment (QMI mode).

Observed behavior

After several hours of normal operation, the modem loses network connectivity. The failure sequence is:

  1. Data session drops (get-data-status: disconnected)
  2. Shortly after, LTE registration is lost:
  • registration: not_registered
  • radio_interface: none
  • AT+CSQ returns 99,99
  • AT+CEREG? returns 0,0
  1. AT+CPIN? reports READY (SIM OK)
  2. USB layer remains operational (device still enumerated as cdc-wdm0 / ttyUSBx)
  3. QMI device accessible but no signal info available

The modem does not automatically recover network registration.

Recovery behavior

The issue is resolved only by performing a radio reset:

AT+CFUN=0
AT+CFUN=1

After this:

  • AT+CEREG? returns 0,1
  • Registration restored
  • QMI data session reconnects normally

USB unbind/bind alone does not reliably recover the modem. A full AT+CFUN=1,1 (modem reboot) also restores functionality.

Summary

This appears to be a radio/NAS stack freeze where:

  • SIM remains ready
  • USB interface remains stable
  • But LTE registration stops and does not resume automatically

We would like to know:

  • Is this a known issue in firmware RM520NGLAAR01A07M4G?
  • Is a newer firmware version available that improves LTE registration stability?

Regards,

Janne

2

Dear @jpknuuti
I have sent a newer firmware to you, please test again.