No. The Gateway appliance private LAN subnet must be 198.168.x.x. The IP address for the Gateway appliance is 192.168.0.1 by default.
You must contact support to change the Gateway appliance private IP address subnet to anything other than 192.168.x.x..
DO NOT USE WEBMIN TO CHANGE THE SUBNET FOR THE GATEWAY APPLIANCE PRIVATE LAN
If you connect to Webmin on the private LAN and change the Gateway appliance IP address to a subnet other than 192.168.x.x, you will be locked out of Webmin, and completely locked out of the Gateway appliance. You must then call support to reset your appliance.