RAK7432 4-20mA Bridge - LoRaWAN Channels

Is it possible to modify the LoRaWAN channel plan for the RAK7432 4-20mA Bridge? Per section 15 of the AT command manual (https://docs.rakwireless.com/Product-Categories/WisNode/RAK7432-RAK7434/AT-Command-Manual/#lorawan-commands) it should be possible.

The device came with default channels US915 8-15+65 (903.9 Mhz - 905.3Mhz), but my gateway uses channels 0-7+64. The device version is 1.1.0069_Release.

When I send the command AT+CHANNEL=0:7 the Node returns “ERROR:1:UNSUPPORT”

Any help would be appreciated.