Question

Hello,

My RUTX50 looses the mobile connection without any apparent reason and doesn't recover without a manual intervention.

The external log server reports:

2023-06-04T21:21:46+02:00 lgr5g netifd: mob1s1a1 (32404): Mobile connection lost!
2023-06-04T21:21:46+02:00 lgr5g netifd: Interface 'mob1s1a1' has lost the connection
...

2023-06-04T21:21:46+02:00 lgr5g netifd: Network device 'wwan0' link is down
2023-06-04T21:21:46+02:00 lgr5g netifd: mob1s1a1 (32041): Stopping network mob1s1a1
2023-06-04T21:21:46+02:00 lgr5g netifd: Network device 'qmimux0' link is down
2023-06-04T21:21:46+02:00 lgr5g netifd: Interface 'mob1s1a1_4' has link connectivity loss
2023-06-04T21:21:46+02:00 lgr5g netifd: Interface 'mob1s1a1_6' has link connectivity loss
2023-06-04T21:21:46+02:00 lgr5g netifd: Interface 'mob1s1a1_6' is now down

....

2023-06-04T21:21:46+02:00 lgr5g mwan3-hotplug[32037]: hotplug called on mob1s1a1 before mwan3 has been set up
2023-06-04T21:21:46+02:00 lgr5g netifd: uqmi -s -d /dev/cdc-wdm0 -t 3000 --set-client-id wds,14 --stop-network 0xFFFFFFFF --autoconnect
2023-06-04T21:21:46+02:00 lgr5g netifd: uqmi -s -d /dev/cdc-wdm0 -t 3000 --set-client-id wds,14 --release-client-id wds
2023-06-04T21:21:47+02:00 lgr5g netifd: uqmi -s -d /dev/cdc-wdm0 -t 3000 --set-client-id wds,16 --stop-network 0xFFFFFFFF --autoconnect
2023-06-04T21:21:47+02:00 lgr5g netifd: uqmi -s -d /dev/cdc-wdm0 -t 3000 --set-client-id wds,16 --release-client-id wds
2023-06-04T21:21:47+02:00 lgr5g ledman[6131]: [handle_wan:543] error: Unable to invoke to `network.interface` dump method
2023-06-04T21:21:47+02:00 lgr5g ledman[6131]: [handle_wan:538] error: Lookup obj `network.interface` err
2023-06-04T21:21:47+02:00 lgr5g ledman[6131]: [subscribe_wan_init:780] error: Lookup obj `network.interface` err

...

2023-06-04T21:21:49+02:00 lgr5g Mobile data disconnected (internal modem)

The TS file is attached. The connection was up again after a manual modem reboot.

Regards,

Answer 1

Hello,

  

At least during the troubleshoot file generation, the device was connected to a mobile cell, however, the RSRP was very poor:

"rsrp": -113, "rsrq": -8, "rssi": -86, "rssnr": 8

The signal was most likely unstable enough for the modem to treat the connection as unusable and simply "disconnect" the mobile interface. 

From your other troubleshoot files I can see that the modem was connected to B3, which seemed to provide a better signal, so I would recommend blacklisting LTE B7 to prevent this issue from happening again.

Alternatively, a ping reboot can be set up, with the internal modem reboot as the action if pings fail. This should also restore the connection.

   

Best regards,
DaumantasG

Comments

The signal may be unstable at times however it shouldn't prevent the system from recovering. Most of the times it uses LTE B3 / 5G N28. 

The root cause seems to be a recurring netifd coredump. Unfortunately the backtrace isn't very helpful:

root@lgr5g:/tmp# gdb /sbin/netifd netifd.1685906506.20138.11.core 
GNU gdb (GDB) 10.1
This GDB was configured as "arm-openwrt-linux".
Reading symbols from /sbin/netifd...
(No debugging symbols found in /sbin/netifd)
[New LWP 20138]
Core was generated by `/sbin/netifd'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00021680 in ?? ()
(gdb) bt
#0  0x00021680 in ?? ()
#1  0x0002934c in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb) 

Attached: one coredump, original timestamp Jun 4 21:21.

I disabled the ping reboot / modem reboot as I am on site I wanted to catch at least one occurence.

---

Hello,

  

I've transferred this case to the developers to look into. I also noticed that the troubleshoot file was removed, perhaps there was something wrong with it?

  

Best regards,
DaumantasG

---

Hello,

  

I've sent you a few firmware files to test if the issue reoccurs via a private message.

  

Best regards,
DaumantasG

---

I have restored the TS file for some unknown reason I haven't been able to attach both the TS and the coredump.

I'll test the fw files ASAP.