grep broadmobi
Yes, the chip is Qualcomm, not the whole modem.
the incantation to execute an AT command is as follows, also showing you how you can check the modem model.
sudo mmcli -m 3 --command=ATI
but unfortunately that didn’t work for me on my phone when I just tried it. Maybe it will work for you.
But getting back to the other mmcli output, does it show the “operator” to be what you expect? What about the “state” and “access tech”?
How did you establish that you have no 4G internet?
ping 8.8.8.8
would be a reasonable test.