Yes, you can often use your existing router with fiber optic internet, but there are crucial considerations. Understanding compatibility, potential limitations, and when an upgrade is necessary will ensure you get the most out of your high-speed connection. This guide will break down everything you. Fiber internet transmits data using light signals through fiber-optic cables, which differs from traditional DSL or cable internet. Instead of a modem, fiber connections require an Optical Network Terminal (ONT), a device that converts fiber signals into an Ethernet connection. It requires a compatible fiber optic modem or ONT. To use it, you'll need a router that supports high-speed data transfer.