[NRF9151] Modem does not connect after SIM deactivate/reactivate

[Mlgr]

Hi,

I’m using the Thingy:91X board with the nRF9151 chip, modem firmware version 2.0.2, and SDK version 2.9.0.

We’re encountering a serious issue: the modem does not reconnect after the SIM has been deactivated and then reactivated.

I’ve tried:

• sys_reboot(SYS_REBOOT_COLD)

• Placing the modem offline (lte_lc_offline())

• Shutting down the modem library (nrf_modem_lib_shutdown())

• Forcing a hard reboot via the watchdog

None of these approaches has worked.

Do you have any suggestions for resolving this issue?

The only workaround so far (which isn’t acceptable) is to manually power the device off and on.

Regards,
Mathieu

[Achim Kraus]

Not sure, how you really tested that.

There may be two pitfalls:

- the reactivation of the SIM may take some time (in some cases more minutes, even longer, especially, if you deactivate and reactivate multiple times in just a few minutes)

- some rejection cause are treated "sticky" by the modem. That requires usually to wait some time or do a "lte_lc_power_off/lte_lc_normal" cycle (but I didn't retest that for a nRF9151)

So, let me propose, that you try to wait a minute or so after reactivate the SIM until you test to connect the modem again. If that results in rejected registrations, then try a "lte_lc_power_off/lte_lc_normal" cycle.

[Mlgr]

Hello Achim,

I let the card run for a few days, but it never reconnected to the network. However, I have a watchdog that reboots the card after “x” minutes without data. Should I disable it? Could it be causing a conflict with the modem in the new version?

I already tried the lte_lc_power_off/lte_lc_normal cycle, but it didn’t work (the watchdog still rebooted the card after a few minutes).

Best regards,
Mathieu

[Achim Kraus]

> EMM cause: 7

=> "EPS not allowed"

And that log is no modem trace ;-).

[Jon]

This happens when i deactivate the sim manually, So this one is okay and happens as expected ;) but the problem occurs after that

[Achim Kraus]

But you will still need to provide a modem trace for that case.

[dejans]

Hi Mathieu,

Here is a list of links from documentation to help you in capturing modem traces:
cellular monitor
capturing modem trace using cellular monitor
capturing modem trace
nrf91 snippets
%XMODEMTRACE set 
modem trace module

Best regards,
Dejan

[Jon]

So, I just couldn’t get modem traces working on the Thingy91X.
Every time I tried to use the required snippet, the build failed with:

undefined reference to `sys_clock_elapsed`

I didn’t want to sink more time into debugging this for now — all I was doing was building the at_client example with the snippet.

Instead, I reproduced the exact same issue on an nRF9151 DK, this time with traces available.

• Trace 1: before a power cycle

• Trace 2: after the power cycle

The test scenario is the same as before:

1. Using a Tele2 SIM card (unsteered, all operators available)

2. SIM is activated at the beginning

3. Then deactivated

4. Perform a few modem power off/on cycles

5. Reactivate the SIM after a while

That’s when the board fails to reattach — even after a full power cycle.

trace1.pcapngtrace2_posPowerCycle.pcapng

Best :)
Jon

[Jon]

Hello :)

Any idea on what we could do ?!

Best !

Jon

[Mlgr]

Hello dejans ,

 Do you have any news about our problem and the Jon's logs?

Best regards,