Check whether the external network cable is normal.

At the same time, test whether the WAN port is normal, connect the WAN port with an internal network cable, and connect the computer at the other end to see if the WAN port is open.

When it is on, it means that the WAN port is normal. You need to check the external network cable to get help from the network service provider.

If it doesn't light up, it means that the routing WAN port is not normal.

Check whether the external network cable is properly plugged into the local computer network card to see if the network card light is on, or plug into the routing LAN port to see if it is on.