What Ports Does a Remote Desktop Use?
You can remote control your computer in one location from a different location with a Windows utility called Remote Desktop. Remote Desktop enables you to use the Internet to access the computer's keyboard, mouse and display as though you were physically sitting at the computer. By default, Remote Desktop communicates with your computer over port 3389. If you use a router, you must forward port 3389 on the router to your computer for Remote Desktop to work properly.
Changing the Remote Desktop Port
If you have two computers on a network you want to remote control, you can use a different port for the second computer. Forward port 3389 on your router to the first computer for standard Remote Desktop access. Select a different port for the second computer, for example, 3390. Forward port 3390 on the router to port 3389 on the second computer. When you launch Remote Desktop from the remote location, type your network IP address to access the first computer or type your network IP address followed by a colon and the port number you selected for the second computer, for example, "74:125:228.177:3390".