Start Registry Editor, and locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber
On the Edit menu, click Modify, and then click Decimal.
Type the new port number, and then click OK.
Quit Registry Editor.
Restart the computer.
Note: When you try to connect to this computer using RDP, you must input the new port.
Origem link