When editing any settings on the TransPort Settings tab of the RD Gateway server properties you get a message saying “Unable to set transport settings”:

This seems to be an as of yet unfixed GUI bug: spiceworks - RD Gateway won't let me change HTTPS Port - Unable to set transport settings.

You will need to edit these settings directly in the registry.

Example to change the UDP port from 3391 to 3392:

1. Open an elevated PowerShell prompt:
2. View the current settings:

   Get-Item "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\TerminalServerGateway\Config\Core"

   1. Output should look like:

      Name                           Property
      ----                           --------
      Core                           AllowNewConnections       : 1
                                     CorpName                  : Microsoft
                                     HttpIPAddress             : *
                                     HttpPort                  : 80
                                     HttpsPort                 : 443
                                     IsaSupported              : 0
                                     IsUdpEnabled              : 1
                                     MaxConnections            : 4294967295
                                     OnlyConsentCapableClients : 0
                                     RAPStore                  : msxml://C:\Windows\System32\tsgateway\rap.xml
                                     UdpIPAddress              : *
                                     UdpPort                   : 3391
                                     RDGConfiguredKDCProxy     : 1

3. Change the UdpPort value to 3392:

   Set-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\TerminalServerGateway\Config\Core" -Name UdpPort -Value 3392

4. Check the value of UdpPort:

   Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\TerminalServerGateway\Config\Core" -Name UdpPort

   1. Output should look like:

      UdpPort      : 3392
      PSPath       : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Term
                     inalServerGateway\Config\Core
      PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Term
                     inalServerGateway\Config
      PSChildName  : Core
      PSDrive      : HKLM

5. Restart the RD Gateway service to apply the change in settings:

   Restart-Service -DisplayName "Remote Desktop Gateway"

6. Don't forget to change the port on the default Windows Firewall rule as well:

   Set-NetFirewallRule -DisplayName "Remote Desktop Gateway UDP Listener" -LocalPort 3392