Hi, please use this AT command to test if it works as you expect it to.
You can execute AT commands with gsmctl -A AT+....
AT+QCFG="lte/bandprior"[,<band1>][,<band2>][,<band3>]
Parameters:
<band1> Band id of first preferred LTE band, range from 1 to 43
<band2> Band id of second preferred LTE band, range from 1 to 43
<band3> Band id of third preferred LTE band, range from 1 to 43
EB.