This is often indicated by the LOS (Loss of Signal) light on the ONT turning red. Fiber Cable Damage: Physical damage from construction, rodents, or weather. ONT Failure: Rare but possible . If the LOS light turns red, it means there's a problem somewhere along the fiber link — maybe a break in the cable, a poor splice, or low signal strength. Fiber optics work by transmitting light through the cable, and that light travels with a. The second problem could be the optical module on the ONT. When the ONU has low Tx optical. Had FTTP since 4th Aug and it's been rock solid until this evening. not something a home owner can fix. Loose Connections: At the ONT, splice closure, or outdoor termination point. The signal shows a full signal, but the network speed is still slow? What does it mean when the ONU indicator keeps flashing? Plug in and light up, showing whether ONU is connected to power, ONU without power connection is useless. If the power supply is normally connected, the POWER indicator.
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