Broadband converted to fiber optic router not working

Your router may not work with fiber internet due to compatibility issues, IP conflicts, or ONT configuration, but systematic troubleshooting can restore connectivity.Check Router CompatibilityFiber internet uses an Optical Network Terminal (ONT) to convert light signals into Ethernet. Your router must have a Gigabit Ethernet WAN port and support high-speed connections. Routers designed for DSL or cable (coaxial) may not work with fiber . Ensure your router is “fiber-ready” or supports the speeds provided by your ISP .Verify Physical ConnectionsConfirm the fiber cable is properly connected to the ONT and the ONT is powered on .Use a high-quality Ethernet cable from the ONT to your router's WAN port.Inspect for bends, cuts, or dust in fiber connectors, as these can cause signal loss .Address IP Conflicts and ConfigurationMany ISPs provide a gateway/router that may conflict with your existing router's IP range (e.g., both using 192.168.1.1), .If the ISP gateway is not in bridge mode, it can prevent your router from obtaining an external IP. Consider:Enabling bridge mode on the ISP gateway so your router handles routing.Changing your router's LAN IP range to avoid conflicts (e.g., 192.168.2.1).Check your router's WAN settings: if your ISP uses static IP, DHCP, or PPPoE, ensure the router is configured accordingly .Test Direct ConnectionConnect a computer directly to the ONT via Ethernet. If it cannot access the internet, the issue may be with the ISP activation or ONT configuration .If direct connection works, the problem is likely router configuration.Restart and Reset DevicesPower cycle the ONT, router, and connected devices.If issues persist, consider factory resetting the router and reconfiguring it for fiber settings .When to Contact Your ISPIf the ONT is not activated or the ISP gateway is not in bridge mode, you may need ISP support to enable proper routing .Fiber installations sometimes require VLAN tagging or authentication, which your ISP can provide.SummaryTo resolve your router issue after switching to fiber:Confirm your router is fiber-compatible with a Gigabit WAN port.Check all physical connections and fiber cable integrity.Resolve IP conflicts by adjusting LAN IP ranges or enabling bridge mode on the ISP gateway.Configure WAN settings according to your ISP (static IP, DHCP, or PPPoE).Test direct connection to the ONT to isolate the problem.Contact your ISP if the ONT is not properly activated or requires special configuration. Following these steps should help restore connectivity and allow your router to function with your new fiber optic internet.