No network connection when the fiber optic box is plugged into the router

If your internet is not working when the fiber optic box is plugged into your router, the issue may be due to power, cable, or configuration problems.Check Fiber Box and Indicator LightsStart by examining the fiber box (also called ONT or Fiber Jack). Look at the LEDs on the device:Power LED off: The box may not be receiving power. Ensure the power cable is fully plugged in and the outlet is working.Optical or PON LED red or off: Indicates a fiber signal issue. Check the fiber cable for kinks, bends, or damage and ensure it is fully seated in the port .Network or Data LED off: Suggests the connection to the router is not established. Verify the Ethernet cable is properly connected to the router's WAN/Internet port .Power Cycle DevicesUnplug the fiber box from power and wait 30 seconds.Unplug the router from power.Reconnect the fiber box and wait 2–3 minutes for it to fully boot.Reconnect the router and check if the internet connection is restored .Inspect Cables and ConnectionsEnsure the fiber cable is not damaged, bent sharply, or loose.Check the Ethernet cable connecting the fiber box to the router; replace it if frayed or damaged.Confirm the Ethernet cable is plugged into the WAN/Internet port on the router, not a LAN port .Router and Configuration ChecksSome routers may fail to obtain an IP address from the fiber box. Rebooting the router can resolve this.Ensure the router firmware is up to date to avoid compatibility issues .If using a fiber-compatible router (e.g., Calix u6), follow the manufacturer's instructions for proper port connections and settings .When to Contact SupportIf after checking power, cables, and rebooting the devices the internet still does not work, or the fiber box shows a persistent red light, contact your internet service provider. They may need to dispatch a technician to inspect the fiber line or replace faulty hardware . By systematically checking power, indicator lights, cables, and router configuration, most fiber internet connection issues can be identified and resolved without professional assistance.