DTLS Handshake Timeout in LWM2M Client

[frambow_i]

We are developing a system were we rely heavily on the use of LWM2M. Using the provided LWM2M client we normally dont experience any problems at all and are able to establish a quick server connection. We recently exchanged our SIM provider and the corresponding apn and are now experiencing way longer server connection establishment times (Multiples of 123 seconds). Looking into the Modem Logs we figured that the TLS Handshake with the RPC_IP_TLS_ATTACH_RES (result RPC_IP_ERR_OK) and the RPC_IP_TLS_HANDSHAKE_COMPLETE_NTF (result: RPC_IP_ERR_NO_ROUTE) might be the culprit here. As I dug into the documentation i figured out that there are many different timeouts for the TLS Handshake. 

My question now is wether there is a working way to configure the timeout in combination with the Lwm2m engine or any other way or if there is another suitable solution for the DTLS problem.

Unfortunately I cant provide modem traces atm because they require more RAM than available.

Thanks in advance for the help,

Flo

[Michal]

Hello Flo,

Which NCS and Modem FW versions are you using?

Are you able to provide the modem trace showing this issue?

Best regards,

Michal

[frambow_i]

Hi Michal, 

We are using the modem fw v2.0.2. and the zephyr v3.5.99-ncs1-2. Unfortunately providing modem traces is not possible at the moment. 

I think all in all there seems to be a problem with the "mobile network backend" of the provider, as we don't see those problems with two other providers. After I found the TLS handshake timeout I thought it might have been a good idea to lower that value to speed up the process. Is that even possible ? 

[frambow_i]

Hi,

At this point we were able to figure out the problem on the network provider side and got everything running again. Thank you for your help either way! 

Best regards, 

Florian