You can use a visual fault locator (VFL), which is a device that emits a red laser light through the fiber, to trace the cable and spot any breaks, cracks, or bends. Fiber optic troubleshooting is an essential skill for network administrators, technicians, and engineers responsible for maintaining and repairing fiber optic systems. These high-speed, high-capacity communication networks are increasingly replacing copper cables, offering superior performance and. A fiber connector left exposed to rain, sun, and temperature swings is a ticking time bomb for your internet connection. The speed test looks. A fiber termination box is the standard instrument used in fiber optic networks to connect, secure, and protect optical fibers at the terminating point. It appears the left is the feed coming from the closet.