Fast pulsing red lights often indicate a factory reset is in progress. The tables in this article provide detailed information about the possible appearances of the LED lights on each device, the possible causes of each state, and what you should do. Red lights on specific ports (like Ethernet) mean. The LEDs on your modem, optical network terminal (ONT), router, or modem/router combo (gateway) are most likely blinking because they're communicating what the device is doing, or there's an error. POWER Normal: Solid/stagnant light. If OFF: The router is not powered — check the socket, adapter, or power cable.