Many fiber internet problems come from dirty connectors or loose plugs, not major faults. Power cycling or restarting your ONT (Optical Network Terminal) often resolves simple troubleshooting internet issues. Use the table below to see expert-recommended first steps for fiber. Fiber optic troubleshooting is an essential skill for network administrators, technicians, and engineers responsible for maintaining and repairing fiber optic systems. Maintenance personnel can refer to this document for step-by-step troubleshooting when dealing with faults arising from the following. A well-built fiber link rarely fails, but when it does the symptoms can be short, confusing, and expensive to chase. However, in real-world installations, whether underground, aerial, or in harsh industrial environments, fiber cables can and do fail. Understanding the common causes of. One of the most frequent problems in fiber optic networks is signal loss —the gradual reduction of optical power as light travels through the cable.