If you have a Netgear Router and encounter the Netgear unknown error 109, you can first reboot the device and check if the problem is resolved. If it still persists, you can follow the series of steps mentioned under:
1. Ensure that all the cables are properly connected to the router and your modem.
2. Check if the router’s firmware is up-to-date. You can download the router firmware and login to the router admin console to update the firmware.
3. Unplug the router’s power adapter from the electric socket and wait for about two minutes.
4. Connect the power adapter back after two minutes and turn the router on to check if the error 109 is resolved.