If your router's recommended fiber optic connection isn't working, the issue could stem from physical cables, the ONT/modem, router settings, or firmware, and systematic troubleshooting is key to restoring connectivity.

Step 1: Inspect Physical Connections

• Check fiber cables for visible damage, sharp bends, or loose connectors. Even minor bends or dust can disrupt the signal .
• Clean connectors using lint-free wipes and isopropyl alcohol to remove dust or oil .
• Ensure the fiber cable is properly connected from the wall outlet to the Optical Network Terminal (ONT) and from the ONT to the router's WAN port .

Step 2: Verify ONT and Router Functionality

• Power cycle the ONT and router: turn them off, wait 30 seconds, and turn them back on to resolve temporary glitches .
• Check indicator lights on the ONT and router. A “LOS” (Loss of Signal) light indicates a connectivity problem .
• If possible, swap transceivers or modules with known working units to rule out hardware failure .

Step 3: Check Router Configuration

• Ensure the router is compatible with fiber input and supports the required SFP or WAN port .
• Update the router firmware to the latest version to prevent compatibility issues .
• Verify network settings such as IP configuration, DHCP, and routing to avoid conflicts .

Step 4: Test Signal and Network Performance

• Use an optical power meter or OTDR to measure signal strength. Values outside the recommended range (typically -15dBm to -30dBm) may indicate a problem with the fiber line .
• If the connection is intermittent or slow, check for environmental factors like temperature extremes, moisture, or interference from nearby electronics .

Step 5: Contact Your ISP if Needed

• If all hardware and configuration checks fail, the issue may be with the fiber line itself or the ONT provided by your ISP .
• Provide your ISP with details about error logs, indicator lights, and troubleshooting steps you've already taken to expedite resolution . By following these steps—inspecting cables, verifying ONT and router functionality, checking configurations, testing signal strength, and contacting your ISP if necessary—you can systematically identify and resolve most fiber optic connection issues.