Yes, a router can work with fiber optic internet. To use it, you'll need a router that supports high-speed data transfer. The router connects to a fiber optic modem or Optical Network Terminal. Some customers may report the speed is limited to 100 Mbps when connected to the TP-Link router, while the speed is much faster and can reach up to 500+ or 900+ Mbps when connecting to the ISP modem directly. If this is what you are experiencing, follow this article to get it resolved. Mark. I had a 1gig fiber connection installed but speeds are only showing around 170mbps. Routers designed for DSL (which uses phone line inputs) or cable (which uses coaxial inputs) won't work. 5 GbE NIC in your PC, NAS, whatever.