BG96 +COPS Registration

I’m using the BG96 device on a RAK5010 device to run custom code to send data to a server. Everything works fine on most devices, most of the time, however I have a number of devices that just stop working.

A device was running for a few days and just stopped working. I put it into debug mode so I can send AT commands directly and it doesn’t seem to be registering on the network.

AT+COPS=1,0,“AT&T”,8

returns: ERROR:30

I’ve tried different working SIMS and different antennas.

How do I figure out where the issue is?

Additional information - this is odd…

22:49:12.980 -> AT+CFUN?
22:49:12.980 -> +CFUN: 1
22:49:12.980 -> OK

22:49:18.279 -> AT+COPS=?
22:49:29.201 -> +COPS: (1,“Verizon”,“Verizon”,“311480”,8),(1,“313 100”,“313 100”,“313100”,8),(1,“AT&T”,“AT&T”,“310410”,8),(2,“T-Mobile”,“T-Mobile”,“310260”,8),(1,“311 490”,“311 490”,“311490”,8),(0,1,2,3,4),(0,1,2)
22:49:29.201 -> OK

22:50:06.253 -> AT+COPS=1,0,“AT&T”,8
22:50:14.094 -> +CME ERROR: 30

22:50:27.316 -> AT+COPS=1,2,“310410”,8
22:50:27.731 -> +CME ERROR: 30

22:51:00.862 -> AT+COPS=2
22:51:00.862 -> OK

22:51:08.616 -> AT+COPS=1,0,“AT&T”,8
22:51:16.397 -> +CME ERROR: 30

22:51:32.773 -> AT+COPS=1,2,“310410”,8
22:51:33.971 -> OK

22:51:58.410 -> AT+COPS?
22:51:58.410 -> +COPS: 1,2,“310410”,8
22:51:58.410 -> OK

22:52:33.623 -> AT+QENG=“servingcell”
22:52:33.623 -> +QENG: “servingcell”,“NOCONN”,“CAT-M”,“FDD”,310,410,29B0911,380,5110,12,3,3,5304,-91,-9,-65,12,32
22:52:33.669 ->
22:52:33.669 -> OK

What’s odd about it is that
AT+COPS=1,0,“AT&T”,8 and
AT+COPS=1,2,“310410”,8

should be the same record. But, selecting Operator by Numeric operator number seems to work, but select by “AT&T” does not.

Why?