Use any dumb terminal like picocom and configure the APN on the modem with AT+CGDCONT=1,"IP","your APN name"
Use AT+QMBNCFG="List" to check if any MBN profile is enabled.
In most cases it is safe to disable autoselection:
AT+QMBNCFG="AutoSel",0
AT+QMBNCFG="Deactivate"
AT+CFUN=1,1