Fiber optic cables transmit light, not power. Your ONT, router, and WiFi depend on local AC power. That's why when the lights go out, your fiber internet power outage disconnects you, even if the provider's system is up and running. Will my provider. Despite their robustness, fiber networks can fail due to: Physical Damage : Cuts, bends, or contamination in fiber cables or connectors. Hardware Failures : Faulty transceivers, switches, or routers. Environmental Factors :. Contact Surf support if the light remains off and you're experiencing issues. What If All Lights Are Off? If none of the lights are on: Check that the ONT is plugged in and the outlet has power. If the ONT still shows no lights, it may be a. There is a single mode optical fiber cable in our datacenter going from a Cisco N5K to another N5K across different racks. The link appears to be dead and I'm hoping to fix it, but I have little to no experience with fiber. This guide offers practical steps to troubleshoot fiber optic cable issues, covering common problems, key tools, and preventive measures to ensure stable performance. A small investment in a battery backup, often called an. Some switches have a solid link light, while others will have both transmit and receive lights that flash as traffic is sent and received, and some switches may have other ways, such as a single light that flashes for traffic in any direction.