Hi friend!
HG8145V5 is a Carrier product.
You are advised to contact your local ISP to check whether your product supports port forwarding. If yes, refer to the following configuration procedure:
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 the following figure:

2. Click Apply.
For more information about port forwarding, click How to configure Huawei ONT port mapping.
Thanks!