This should be the light cat power and the registered light is on without a net:
1, first try to plug the network cable directly into the 100 megabit port to connect the computer to observe whether there is a network there is a network to see the second step no network is likely to be broadband arrears
2, if the router is connected to the optical cat, and then the computer is connected to the router without network This need to set the router lan port to prevent ip conflict if the optical fiber line is faulty optical cat will have a red light flashing
Reboot. If that doesn't work, call customer service.