Connect Nighthawk M1 via USB to your computer. Open up a terminal and connect to the Nighthawk M1 via telnet (IP MAY VARY):
telnet 192.168.1.1 5510.
You can check the current status of the LTE via the AT!gstatus? command.
To add more options to your cellular list in the Nighthawk M1 settings, copy/paste the following commands and paste them in the telnet session (you might need to hit ENTER one or two times - just as long until no "OK" comes back):
AT!BAND=3,"1800 Only (B3)",0,4
AT!BAND=4,"2600 Only (B7)",0,40