Assume we have a computer in our local network. Let its IP address be 192.168.1.2. The other computer from the outside wants to connect our computer via port number 3389. After connection arrives to the router, then connection is broken because router does not know where to forward this incoming connection. To forward this incoming connection to the computer in our local network, we need to define port forwarding rule to our router. By doing so, we tell router that if you take any connection request including port 3389, forward it to the computer with the IP of 192.168.1.2. As a result, router can forward incoming request with port 3389 to the computer with IP address of 192.168.1.2. Helpful Video