Problem Running Demo Program on nRF91X Thingy

RE: Problem Running Demo Program on nRF91X Thingy

rblackner — Tue, 19 Aug 2025 18:19:57 GMT

Hi,

I’m testing the Thingy:91 X alongside an nRF9151 DK. On the DK, I can attach to LTE without issues using multiple SIMs, but when I move the same SIMs over to the Thingy:91 X, the device hangs indefinitely with the yellow LED flashing (searching for LTE).

What I’ve tried so far:

4 different SIM cards (2× Conexa, 2× Onomondo)
- All work fine in the nRF9151 DK
- None attach when inserted in the Thingy:91 X
Followed the Quick Start flow in nRF Connect for Desktop (Start Prototyping)
Power cycling, reprogramming via Quick Start, and trying different APN settings
AT commands over UART are accepted
Tested with and without band locks (no change)

Cellular Monitor behavior:

On the DK, I captured a modem trace and did see an error (attached) perhaps this might help.
On the Thingy:91 X, Cellular Monitor seems to get stuck on the initial “TRACE” step and does not progress.

Question:
Since the SIMs and network attach correctly on the DK, what could prevent the Thingy:91 X from attaching? Are there extra steps (firmware alignment, bridge firmware, antenna configuration, etc.) that I may have missed in setup?

Attachment:

devzone.nordicsemi.com/.../trace_2D00_2025_2D00_08_2D00_19T18_2D00_06_2D00_59.190Z.mtrace

RE: Problem Running Demo Program on nRF91X Thingy

SoTXhelp — Mon, 18 Aug 2025 19:33:41 GMT

Hello Reily,

Sorry to hear that you are having issues connecting with the Thingy91X.

I generally run AT+CEREG=5 to turn on notifications related to network connections. If I am mobile this will update me when I am moving between cells or if I drop from coverage. This automatically updates on changes to the tower connection.

AT%CESQ=1 will auto update on RSRP (Signal quality)

I suggest running Cellular Monitor so that you can capture a trace of the connection. This will provide much more diagnostic information for us to evaluate what is happening.

Were you successful connecting with the nRF9151DK board with a SIM? If so, use the same SIM on the Thingy91X and try again.

It can take over 15 minutes for the SIM to update to a new local profile the first time it is uses. Once configured it should attach rapidly.

We are wanting to see +CEREG indicate 5,1 (home network) or 5,5 (roaming network).

In Nordic nRF Connect for Desktop you would open cellular monitor, select the Thingy91X. Then select start. Using a program from QuickStart automatically enables trace capture. You should see the indication at the bottom of the screen where the file size should be incrementing. This is a binary file. It should be shared here so we can see what is happening in your network.

Regards,

Don

RE: Problem Running Demo Program on nRF91X Thingy

rblackner — Mon, 18 Aug 2025 17:23:31 GMT

Started exploring the AT commands a little more. My understanding of the following is that 5,4 means we are still searching.