Routers with WAN/LAN Ethernet adaptive ports sometimes fail to detect the plugged home network cable during the initial setup for internet access.
For your reference, here are some troubleshooting methods:
1. Please select custom mode (no network cable). After configuring the Router, please enter 192.168.31.1 in the web browser to access the router's system. Go to [Common Settings] >> [Internet Settings], and set it as a fixed WAN port. After setting up, please connect the network cable and check whether the issue persists.
2. Please replace another Optical Network Terminal and plug in the network cable again.