I have been able to use the solution documented in this (Portenta H7 - Cat. M1/NB shield does not connect over LTE Cat-M1 - Portenta / Portenta CAT.M1/NB IoT GNSS Shield - Arduino Forum) thread to set the frequency bands via the AT commands and the SerialPassthrough sketch. The problem is that the GSM library provided by Arduino to communicate with the module looks to reset the bands to only enable B20. How can I set the modem to use different bands? If I set the bands via AT commands prior to calling GSM.begin somewhere buried with the begin method the band is being reset to B20. In this ( Any Chance for debugging of CatM1/NB Shield - Portenta / Portenta CAT.M1/NB IoT GNSS Shield - Arduino Forum) thread it is suggested to use GSM.sendAT, but that is not within scope for the Portenta GSM library. Any insight is appreciated. Thank you!