Cellular modem hangup after 24h and lora_pkt_fwd stop to send packets

[Thierry Quemerais]

Hi,

We have a strange issue with cellular modem (LTE) and the lora_pkt_fwd.
We are using a MTCDT-LEU1-247A-EU with AEP 1.4.3 firmware and Celluar as WAN.
We properly setup LTE and lora_pkt_fwd (Keep alive = 1) etc …

Everything is working properly during exactly 24h, then after that the modem hangup and will reconnect immediatly, however once this behaviour happen no more UDP packets are received from LoRa Server.

However, if we try to ping a public IP, everything is working and if we manually restart the lora_pkt_fwd (kill it then relaunch it), everything is working again for 24h.

So, it seems that the cellular modem reconnect properly and the internet connection is available again however the lora_pkt_fwd seems to be in a strange state.

Did you ever meet this issue ?

Best regards,
Thierry.

PS: We will provide more logs and tcpdump for a better understanding. ( In 24h 😉 )

[Thierry Quemerais]

Hello,

After deeper investigations we finally found the problem and we will need multitech help to fix it properly.

The problem come from the lora_pkt_fwd and not the 4G itself.
In fact, the lora_pkt_fwd will not reopen/rebind the socket when an interface/route will change.
So, if the lora_pkt_fwd start and only 1 interface is available (i.e: ethernet) then it will bind on this interface, then if the wifi become up later, the gateway might switch to the wifi interface (Depending to the failover rules) but in this case the lora_pkt_fwd will stop to transmit packet because it was initialy bound on the ethernet only.

A quick fix should be to restart the lora_pkt_fwd everytime a route is changed or an interface is changed (i.e 4g interface is disconnected/reconnected).

Can multitech include this fix in the futur firmware version ?
Or can you let us know if you have any hook/event we can use to be alerted when something change (interface/route) ? and we will do the job.

Thank you,
Best regards,
Thierry.

[Jason Reiss]

There is a setting in the packet forwarder that can be enabled to quit the packet forwarder if the network server cannot be reached after a series of “keepalive_interval” checks.

Add this setting to the “gateway_conf” section to enable the autoquit
“autoquit_threshold”: 30

On AEP the angel process will restart the packet forwarder after it quits.

We are updating our examples to include this setting.

[Thierry Quemerais]

Hi,

Thanks you for your quick reply.

This fix is acceptable for us, we will try it and let you know the result.

Thank you,
Best regards,
Thierry.

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