If your fiber optic terminal box (ONT) is not working, start by checking power, inspecting cables, and performing a reset before contacting your ISP.

Step 1: Check Power and Connections

Ensure the ONT is properly plugged in and receiving power. Look for a green or blue indicator light; if no light is visible, try a different power outlet or power cord. If the ONT is connected to a GFCI outlet, press the reset button on the outlet and test again. Confirm that all connected devices, such as routers or computers, are unplugged during this process to prevent data loss or damage .

Step 2: Inspect Fiber Cables

Examine the fiber optic cable for visible damage, bends, or kinks. Fiber cables are fragile, and even minor physical damage can cause signal loss. Ensure the connectors are clean and securely plugged into both the ONT and the wall socket. Use lint-free wipes and isopropyl alcohol to clean connectors if necessary .

Step 3: Check Indicator Lights

Most ONTs have status lights labeled for power, fiber, internet, phone, or TV. A “LOS” (Loss of Signal) light indicates the ONT is not receiving a valid optical signal. If lights indicate a problem, it may point to a cable issue, hardware failure, or network outage .

Step 4: Restart or Reset the ONT

Perform a power cycle by unplugging the ONT for 30 seconds and then plugging it back in. If the issue persists, use the reset button on the ONT (consult your user manual for its location). This can resolve intermittent connectivity, slow speeds, or configuration conflicts .

Step 5: Test Signal Strength and Hardware

If the ONT still does not work, advanced diagnostics may be needed. Use a power meter or OTDR to measure signal loss. Values outside the normal range (-15dBm to -30dBm) may indicate a problem with the fiber line. Swap suspect transceivers or routers with known-good units to isolate hardware failures .

Step 6: Contact Your ISP

If all steps fail, contact your internet service provider. They can check for outages, verify your ONT configuration, or replace faulty equipment. Avoid attempting internal repairs on the ONT, as it is typically installed and maintained by the ISP . By following these steps—checking power, inspecting cables, monitoring indicator lights, performing resets, and testing signal integrity—you can often restore your fiber optic connection or identify when professional assistance is required.