Hello,
You can set port forwarding on the WAN Configuration page.
1. In the navigation tree on the left, choose Forward Rules > Port Mapping Configuration. In the pane on the right, click New. In the dialog box that is displayed, set the parameters related to port mapping, as shown in Figure 1.

2. Click Apply.
Port mapping indicates that the Intranet server is allowed to be open to the Extranet (for example, the Intranet provides the Extranet with a WWW server or FTP server). Port mapping is to map the Intranet host IP address and port ID to the Extranet IP address and the corresponding port ID so that users from Extranets can access the Intranet server.
With port mapping, the users cannot see the Intranet IP address. They see the Extranet IP address.
Thanks