Port Redirection is used access internal servers from the Internet. Internet hosts use the WAN IP address of the router to access internal network services. For example a web server you may be hosting locally. Requests from the Internet are mapped to the private IP address/port of the internal server.
Note: Port redirection only applies to incoming traffic
You can forward a different external port to the port of your internal Server/PC. This allows you to have more than one internal server using the same port number.
This video shows you how to configure a DrayTek Vigor router so that a web server and a VNC server hosted on the local LAN so that they can be accessed from the Internet. The example uses a DrayTek Vigor2860 but the same procedure can be used for other DrayTek router models.
Click here to watch this video.