This happens when the signal weakens as it travels through the cable, leading to slower data transmission and unreliable connections 1. What causes it? How to fix it: Inspect cables for sharp bends or kinks and gently straighten them. Use bend radius protectors during. In this guide, we'll walk you through a series of simple steps that can help you identify and resolve the most frequent culprits behind slow fiber internet speeds so you can get back to enjoying your online activities without interruptions. If your fiber optic internet isn't performing as well as. If you're dealing with slow internet speeds after replacing an old router with a new one and wondering “Why is a new router even slowing down my internet?”, we're here to share something that we worked out recently and hope it will help you also. There are many reasons why you may have a slow. However, since it got installed and we configured the new router, the internet is rather mediocre, definitely not what we expected. The advertised speed is 10MB/s (I'm from Costa Rica and these speeds are quite normal here) and while loading videos, apps, etc, it works very well, almost instant. Got new internet three days ago, 1gb download and 100mb upload. But you might find your fiber internet or optic speeds lagging.