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. 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. Compatible router: Verify that your router supports fiber optic input (look for an SFP or WAN port labeled. The process to connect fiber optic cable to router requires careful attention to detail, but I'll walk you through every critical step with the precision and clarity you deserve. I never received it from Telekom, as well as Access number (Zugangsnummer).