1. Open up Registry Editor by clicking on the Start Button, type in regedit and then hit Enter.
2. In Registry Editor, navigate to HKEY_LOCAL_MACHINE, SYSTEM, CurrentControlSet, Control, Terminal Server, WinStations and RDP-Tcp. 
3. Right click on the PortNumber dword and select Modify. 
4. Change the base to Decimal and enter a new port between 1025 and 65535 that is not already in use.
5. Click OK and reboot.