If you experience problems connecting to that system, because a Firewall is blocking that port 3389, then you can change the port number used to a different number.

Changing the standard port number to another number is also a good security practice, because it is not obvious to hackers which port is being used.

To change that port number:

1. Start a registry editor (e.g., regedit.exe).
2. Navigate to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TerminalServer\WinsStations\RDP-TCP registry subkey.
3. Find the entry for "PortNumber" on the right.
4. Double-click it and select the Decimal radio button.
5. Change it to another Decimal number, like 3390
6. click OK.

Once you have changed the port number, you can no longer connect to the remote system just by providing the systems name.

You will also have to provide the new port number on the connection attempt as indicated in the picture below