For LOS (Loss of Signal) red lights on fiber or advanced gateways, it usually means the incoming optical line is not detected or has low signal. Double-check that the fiber line is connected properly and that there's no bend or physical damage. When it's green and steady, everything. Routers typically have several lights indicating the status of the power, internet connection, Wi-Fi, and other functionalities. The common statuses for these lights are: NSI-79750LW Round Indicator Light with Non Replacable Lamps, Press Fit, 0. However, when it blinks red or stays solid red, it signifies a Loss of Signal, a problem preventing your router from communicating.