The fiber optic cable is not working after being plugged into the router

If your fiber optic cable is not responding when plugged into the router, the issue could be due to physical damage, loose connections, faulty hardware, or configuration errors.Step 1: Inspect Physical ConnectionsEnsure the fiber optic cable is properly seated in both the router and the ONT (Optical Network Terminal). Unplug the cable, check for dust, debris, or bent connectors, and reinsert it firmly until it clicks into place. Look for visible damage such as kinks, pinches, or frayed ends, as even minor bends can disrupt signal transmission .Step 2: Check Indicator LightsExamine the router and ONT LEDs. A “LOS” (Loss of Signal) or red optical light indicates a connectivity problem. Solid green lights typically mean the devices are powered and the fiber link is active . If the optical light remains red after reseating the cable, the issue may be with the fiber line or transceiver.Step 3: Test Hardware ComponentsSwap the fiber transceiver or router port with a known working unit if available. Faulty transceivers, routers, or switches can prevent the fiber from establishing a connection . Restart the router and ONT to clear temporary glitches.Step 4: Clean ConnectorsUse a lint-free wipe and isopropyl alcohol to clean the fiber connectors. Contamination from dust or oils can block the optical signal .Step 5: Verify ConfigurationEnsure the router is connected to the correct WAN or Internet port and that firmware is up to date. IP conflicts or outdated firmware can prevent the router from recognizing the fiber connection .Step 6: Advanced TestingIf the above steps fail, use a fiber power meter or Visual Fault Locator (VFL) to measure signal strength and locate breaks or attenuation points in the cable . Persistent issues may require contacting your ISP or a service technician to inspect the fiber line. By systematically following these steps, you can identify whether the problem lies with the cable, the router, or the network infrastructure and take appropriate corrective action.