Discrepancies in Modem Network Connection on Two Modules Using the Same SIM Card

[Unicorne3000b]

I am experiencing an issue with establishing a modem network connection on two different versions of the board that I am using:

• Board A: As soon as I insert the SIM card, I immediately obtain a stable internet connection, and everything works as expected.

• Board B: Using the same sketch and the same SIM card, I am unable to get an internet connection. The program is intended to run identically on both boards, yet the internet connection fails on the board B.

Is there any way to check Firmware versions of the Modem or ESP?

[FallingSnow]

Are you looking for AT+CGMR as described in the manual? You can run that command with the ATDebug sketch.

[lewisxhe]

AT+SIMCOMATI to check the firmware version. For information about connecting to the network, see this issue

#90

[Unicorne3000b]

Thanks for the hints. I have tried the commands with following response:
Board A (working as expected):

AT+SIMCOMATI
Revision:1951B17SIM7080
CSUB:B17V01
APRev:1951B17SIM7080,B17V01
QCN:SIM7080G_P1.03_20210823
IMEI:860016048820547

AT+CSQ
+CSQ: 17,99

AT+CNMP?
+CNMP: 2

AT+CMNB?
+CMNB: 1

AT+CBANDCFG?
+CBANDCFG: "CAT-M",1,2,3,4,5,8,12,13,14,18,19,20,25,26,27,28,66,85
+CBANDCFG: "NB-IOT",1,2,3,4,5,8,12,13,18,19,20,25,26,28,66,71,85

AT+CEREG?
+CEREG: 0,1

Board B (not registering):
AT+SIMCOMATI
Revision:1951B17SIM7080
CSUB:B17V01
APRev:1951B17SIM7080,B17V01
QCN:SIM7080G_P1.03_20210823
IMEI:860016048841212

AT+CSQ
+CSQ: 19,99

AT+CNMP?
+CNMP: 2

AT+CMNB?
+CMNB: 1

AT+CBANDCFG?
+CBANDCFG: "CAT-M",1,2,3,4,5,8,12,13,14,18,19,20,25,26,27,28,66,85
+CBANDCFG: "NB-IOT",1,2,3,4,5,8,12,13,18,19,20,25,26,28,66,71,85

AT+CEREG?
+CEREG: 0,2

i can't see a difference in the cband config, but CEREG state won't change from 0,2. I am using the same SIM card for both boards.

[lewisxhe]

Check the return values ​​of these two commands again

1. AT+CGNAPN
2. AT+NBSC?

[Unicorne3000b]

Thanks, the APN field was empty on Board B.
After running AT+CGDCONT it is now registering.
I did not have to use AT+CDDCONT on board A and another one, so i assumed it updates itself automatically.

[lewisxhe]

It's good to be solved.