Recently during a DR Test we wanted to change the Address on the RDP file that was being downloaded for the Remote Desktop Gateway.
Someone has put together a nicescript that can do it here :
However the file still has the old address in this line : gatewayhostname:s:
You can change this using powershell per below
Set-RDSessionCollectionConfiguration -CollectionName “Finance Staff RDP” -CustomRdpProperty “gatewayhostname:s:rdssb.office.domain.com“