How to check router and fiber optic connections

To check a fiber optic connection to your router, inspect the physical connections, verify ONT and router status lights, and optionally use a fiber optic power meter or signal tester.

Step 1: Inspect Physical Connections

Ensure that the fiber optic cable is securely connected at both ends—into the wall outlet and the Optical Network Terminal (ONT), and from the ONT to your router via Ethernet. Look for any visible damage such as cuts, bends, or kinks in the fiber cable, as these can cause signal loss or connection issues . Remove any dust caps and make sure connectors are clean and properly seated.

Step 2: Check ONT and Router Status Lights

The ONT converts the optical signal into an electrical signal for your router. Power, link, and data lights on the ONT should be solid or blinking green, indicating a healthy connection . Similarly, the router's WAN or Internet light should indicate an active connection. If lights are off or red, the connection may be faulty or the ONT may not be receiving a signal.

Step 3: Test Signal Strength (Optional)

For a more precise check, use a fiber optic power meter or Optical Loss Test Set (OLTS). Connect a jumper cable from the ONT or fiber source to the meter, press the test button, and compare the readings. A significant difference between transmitted and received power indicates signal loss or a degraded fiber line . A visual fault locator can also help detect breaks or bends by shining light through the cable.

Step 4: Verify Internet Performance

Run an online speed test using tools like Speedtest.net or Fast.com. Fiber connections typically provide symmetrical speeds, meaning upload and download speeds are nearly identical. If upload speeds are much lower than download speeds, the connection may not be fully fiber or there may be an issue with the ONT or router .

Step 5: Confirm Router and ONT Configuration

Ensure your router is compatible with fiber internet and connected to the ONT's Ethernet/LAN port. Check the router's WAN settings and update firmware if necessary to maintain optimal performance . Proper placement of the router in a central, ventilated location can also improve connectivity. By following these steps—physical inspection, status light verification, signal testing, speed checks, and router configuration—you can effectively check and ensure your fiber optic connection to the router is functioning correctly.