The foundation of any successful fiber setup lies in understanding the conversion process: optical signals must be transformed into electrical signals your router can interpret. This conversion happens either through an Optical Network Terminal (ONT) or directly via specialized router. To connect your fiber optic cable to a router, ensure you have the following: Fiber optic modem (ONT): Most fiber connections require an Optical Network Terminal (ONT), provided by your ISP. Do You Need a Modem for Fiber Internet? The short answer is no – fiber internet doesn't need a modem. Unlike CAT-6 cable routers, fiber optic cables transmit light signals due to.