You can change the default RDP listening port from 3389 to another value by editing the registry.
- Start Registry Editor.
- Find and then click the following registry subkey:
- On the Edit menu, click Modify, and then select Decimal.
- Type in the new port number (for example 3390) and then click OK.
- Quit Registry Editor.
After making the change you will need to connect to the computer by appending the port number to the end of the name or IP address. For example my.computername.com:3390