I did both a web factory reset, then a hard reset. After the first reset the device stopped pulling an IP from AT&T. I ran the carrier switch wizard, but it didn’t seem to help. The modem sees the SIM and identifies the IMSI, but that’s as far as it goes.
Is there some setting that is configured when the modem is shipped as that get’s changed on a factory reset?
You might have wiped the APN out. Go to Configuration - Network > Interfaces > Mobile > Mobile Settings and look for “Service Plan / APN”
You would need to enter the AT&T APN to join their network.
You could try “broadband” or “phone” which are two common ones.
Apply, then Save, then reboot and see what happens.
Changing the APN to ‘phone’ and removing the optional log in information did the trick. What’s interesting is that I did not have to complete this step when I set up the modem initially. Either way, thank you very much.