Serial commands to EM7411 on Panasonic Toughbook

I’m trying to replace an EM7411 in a Panasonic Toughbook (model FZ-55). The GPS of new EM7411 works but cellular will not connect to ATT/Firstnet. Windows device drivers load and look correct but it won’t connect to the cellular network.

I thought to try some AT commands to query the module. Using a terminal program, what do I connect to? I tried connecting to the GPS COM port but it outputs a continuous stream of GPS data so I can’t enter commands to see what the response is. I tried connecting to the DM COM port but it doesn’t respond. Thanks.

AT command should be entered in modem port, not nmea port