Disconnect the fiber-optic cable and reconnect it to the device if simply tightening the connection fails to remedy the problem. Why Do Fiber Networks Fail? Despite their robustness, fiber networks can fail due to:. This guide outlines proper methods to safely remove fiber optic cable from modems in your home or office. Before diving into solutions, it's crucial to understand what an optical cable is and how it works. Let's dive into the most frequent headaches, how to spot them, and, most importantly, how to get your network back on track.