Open the Registry Editor
Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp
Click ok and close the registry editor.
By the way: U have to add a Firewall Rule for the new port to Windows Firewall…
now you have to restart the server or restart the “Remotedesktopservices” under the Windows Services but befor u test it: You should have physic access to the server, if something went wrong!
If you don’t have this option, install TeamViewer or something like that.. so u could return the changes in the registry.
If it works, deactivate the old RDP Firewall Rule in the Windows Firewall.