If the Alarm light is red, it's likely that the ONT has detected an error or fault. Restart the ONT to see if the issue resolves itself. Thank you I think there is some wide outage going on in the bay area. Nope, only fix is to switch ISP's. Frontier. The lights on your ONT are typically LED indicators that display different colors and patterns to convey information about the device's status. What Can I Do? First, please check that the optical cable which comes. This guide will walk you through what the LOS light means, why it blinks red and step-by-step instructions on how to resolve the issue, including resetting your router. Not sure if you have an ONT? The video below can help you identify if you have one. Of course, specialists from the company from which I got the service were called.