No internet connection with Xiaomi router using dual fiber optic connections

Connectivity issues with Xiaomi routers on fiber networks often stem from VLAN misconfiguration, IP/DNS settings, or physical fiber link problems.Check Physical ConnectionsEnsure that all fiber optic cables are properly connected and undamaged. Inspect connectors for dust or bends, as even minor contamination can disrupt the signal . Verify that the router's Ethernet port is connected to the ONT (Optical Network Terminal) and that the relevant indicator lights for both the router and ONT are on . If using dual fiber connections, confirm that only one active WAN port is configured to avoid conflicts.Verify Router SettingsWAN IP and DNS: Log in to the Xiaomi router's web interface (via miwifi.com or router.miwifi.com) and check the WAN IP address. If it is invalid, set the primary DNS to 8.8.8.8 and secondary DNS to 8.8.4.4 .VLAN Configuration: Many fiber ISPs require a specific VLAN ID (e.g., VLAN 10) for internet access. On Xiaomi routers, this can be set in the network settings under WAN or Internet configuration. Without the correct VLAN, the router may show a connected light but fail to access the internet .Firmware Updates: Ensure the router is running the latest firmware to avoid compatibility issues with fiber services .Test Internet ConnectivityConnect a computer directly to the ONT using an Ethernet cable to confirm that the fiber service is active. If the internet works directly, the issue is likely with router configuration .Restart both the ONT and the Xiaomi router to clear temporary glitches .Additional TroubleshootingReset the router to factory settings and reconfigure it, ensuring only the required WAN port is active .If using OpenWrt or custom firmware, ensure VLAN and WAN interface settings match the ISP requirements .Check for IP conflicts or multiple active connections that may prevent proper routing . If these steps do not resolve the issue, contact your ISP to confirm the correct VLAN ID, PPPoE credentials, or any special configuration required for dual fiber connections .