RAK5010 Network Connection and SIMs

Issue: 3 of my RAK 5010 board are having difficulties in connecting to the network. AT+CREG always returns 0,2. I have 20 of these devices and 17 are working perfectly fine. I thought this might have been a SIM issue but I narrowed it down to 2 new devices and one older device that is having a connection issue.

Setup: Using known working SIMs from another RAK5010, move that SIM over to the questionable RAK5010 and run the same program. All configurations look to be identical but device never connects to the network. I tired with 3 known working SIMs, all results are the same. Return that SIM to the known working device and it connects without any issue.

Details: I discovered that all the new boards came with AT+CFUN? returning 5, so I reset that (QRFTESTMODE=0) and 8 of the new boards worked fine afterwards. 2 still exhibit problems. I’ve let the board sit for a long time trying to register w/o any positive results.

So, the question is, how can I double check that a board the works does have exactly the same settings as a board that isn’t? (I’ve done AT&F to try to set settings to factory). I’ve also looked at the QCFG settings to verify that they are the same.

The other question is - a board that was working perfectly fine just stopped working. Is that possible? What items should I be looking for?

We’re getting ready to create a bunch of devices based on the RAK5010 (Arduino and custom software) and it seems to be working really well. I just want to make sure we’re not missing something.

Thanks.

@InlineTechnology
Please check your power supply. I had problems when I used a power supply from a USB hub.
I used the AT command AT+CFUN=1,0 on Quectel BG77 but I haven’t tested this AT command on the rak5010.
Also compare the value returned by the AT+CSQ (Signal Quality Report) on the boards that work and the boards that have a problem.