Serial LTE Modem does not connect to the network on nRF9161

[Jan Kowalewski]

Hello,

I'm trying to use SLM application on ctcc/nrf9161 hardware (https://github.com/nrfconnect/sdk-zephyr/tree/main/boards/ct/ctcc) however it seems I'm not able to connect to the network.

Setup:

- nRF SDK v2.8.0

- nRF9161 modem firmware 2.0.2 (latest)

For cross testing I used nrf9160dk (unfortunately I don't have 61):

- nRF SDK v2.8.0

- nRF9160 modem firmware 1.3.7

I'm using AT commands to configure chips, flow is the same for both ctcc/nrf9161 and nrf9160dk:
- AT+CEREG=5

- AT+CGDCONT=0,"IP","rh"

- AT+CFUN=1

On nrf9160dk I have no issues with connections, it successfully discovered BTS, get IP etc. (CGATT is 1, there is IP on CGDCONT, PDP context active) and XPING works fine. So I'm sure that APN and my SIM provider is fine.

When it comes to ctcc/nrf9161 unfortunately it never connects to the network, it is stuck at:

+CEREG: 5,2,"DEBC","0423510A",7

And never connects to the internet, even when trying to enforce operator, settings CGATT=1 etc. I did also factory reset on both ctcc and dk and it's all the same. DK works ctcc not. The SLM is not modified, I'm not using any overlays, just "west build -b ctcc/nrf9161/ns" and for dk accordingly.

BR,

Jan

[Øyvind]

Hello Jan, 

Could you please provide full Serial LTE Modem logs from the CTCC/nRF9161 HW? 

- AT+CGDCONT=0,"IP","rh"

Any difference if you test with IPV4V6 – Virtual type of dual IP stack? 

And never connects to the internet,

How long are you letting it try to connect to the network?

Thank you.

Kind regards,
Øyvind

[Jan Kowalewski]

Hello,

this is how it looks like on ctcc/nrf9161:

*** v3.7.99-ncs1 ***
[00:00:00.257,110] <inf> at_cmd_custom: Custom AT commands enabled with 70 entries.
[00:00:00.262,847] <inf> fs_nvs: 2 Sectors of 4096 bytes
[00:00:00.262,847] <inf> fs_nvs: alloc wra: 0, fe8
[00:00:00.262,878] <inf> fs_nvs: data wra: 0, 0
[00:00:00.507,171] <inf> slm: lib_modem init: 0
[00:00:00.507,232] <inf> mcuboot_util: Image index: 0, Swap type: none
[00:00:00.507,263] <inf> slm: Serial LTE Modem
[00:00:00.594,207] <inf> nrf_cloud_info: Device ID: 50334756-3437-41ee-80fa-1c1ee3c4454d
[00:00:00.599,578] <err> nrf_cloud_info: Error requesting the IMEI: 65536
Ready
[00:00:00.691,680] <inf> nrf_cloud_info: UUID: 50334756-3437-41ee-80fa-1c1ee3c4454d
[00:00:00.697,723] <inf> nrf_cloud_info: Modem FW: mfw_nrf91x1_2.0.1
[00:00:00.697,753] <inf> nrf_cloud_info: Protocol: MQTT
[00:00:00.697,784] <inf> nrf_cloud_info: Download protocol: HTTPS
[00:00:00.697,814] <inf> nrf_cloud_info: Sec tag: 16842753
[00:00:00.697,845] <inf> nrf_cloud_info: Host name: mqtt.nrfcloud.com
[00:00:00.697,937] <inf> slm_uart_handler: UART baud: 115200 d/p/s-bits: 3/0/1 HWFC: 0
[00:00:00.698,059] <inf> slm_at_host: at_host init done
> AT+CGDCONT=0,"IPV4V6","rh"

OK
> AT+CEREG=5

OK
> AT+CFUN=1

OK
> AT+CEREG?

+CEREG: 5,4

OK

+CEREG: 2,"DED1","0288DA39",7
> AT+CEREG?

+CEREG: 5,2,"DED1","0288DA39",7

OK
> AT+CGDCONT?

+CGDCONT: 0,"IPV4V6","rh","",0,0

OK

I know it says 2.0.1 modem firmware, I tried to use previous version to see if there is a difference, but unfortunately not. I'm waiting like 30mins at least, what is strange that for nrf9160dk once it sees BTS it quite quickly registers to network.
What is interesting is this error regarding IMEI, on DK I don't have this error.

BR,

Jan

[Jan Kowalewski]

I think I found the issue, I was not aware that nrf91 do not come with IMEI. I found the documentation: https://docs.nordicsemi.com/bundle/nrf-cloud/page/ImeiManagement/Ordering/OrderingImeis.html about this. I think this is the root cause.

BR,
Jan