Hi friend, I've found some configuration methods that I hope can help you.
You can configure port mapping on the WebUI
1. Use a provided Ethernet cable to connect a LAN port of the ONT to the PC
2. Obtain an IP address automatically using the PC and make sure that the IP address of the PC is in the same subnet as the management IP address of the ONT
3. Log in to the Web configuration interface
Enter http://192.168.100.1 in the address bar of IE, and then press Enter to display the login interface
In the login interface, enter the user name and password. After the password authentication is passed, the Web configuration interface is displayed
4. 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
5. Click Apply

Thanks.