Server socket silently stop working after GPS search

[sfrank]

Modem fw version: nrf9160_1.2.1

How to reproduce:

- Set AT%XSYSTEMMODE=0,1,1,0

- Open a TCP IPV4 server socket in a thread and wait for connection (i.e. accept). The zephyr echo server sample can be used as reference.

- Verify the socket works.

- Start a GPS scan/search (I used gps_control_start())

Problem: Unable to connect to device. I would expect `accept` to wake up the thread and return -1 or, preferably, that my server socket was still working.

I do not see any warnings or errors in log.

Sorry if this is already a known issue, I could not find it.

[Hakon]

Hello,

do you have PSM or eDRX enabled on the device when running the GPS? If you want to use them concurrently you will need to have either PSM or eDRX enabled.

[sfrank]

Thanks for the reply! It sounds like this is supposed to work.

I have CONFIG_GPS_CONTROL_PSM_ENABLE_ON_START=y (i.e. `lte_lc_psm_req(true)`). Could it be that PSM is not supported by the provider?

[Hakon]

sfrank said:

Could it be that PSM is not supported by the provider?

 Could be. What SIM are you using? Is it a roaming SIM?

[sfrank]

Telia. Yes it is a roaming SIM.

I think this might be related to the provider. I get occasional errors like this:

lte_lc: Could not get TAU, error: -22

lte_lc: Failed to parse PSM configuration, error: -22

They started to appear after I first posted but there have been other issues with the network. Unfortunately I do not have time to investigate this further right now so I disabled the GPS.

I still believe `accept` should return error if the socket is dead and will never recover.

[Hakon]

sfrank said:

Telia. Yes it is a roaming SIM.

 There is a possibility that the network will block the device from entering PSM if it is roaming. The errors codes you mentioned indicate that the device is unable to enter PSM. You should probably contact Telia if you want to confirm this.