FTTP ONT red light often indicates optical signal loss or fiber cable connection issues. First, check the fiber optic cable for bends, damage, or loose connections at the. If you find that the Optical/Config/PON Light on your Fibre ONT (Optical Network Terminal) box is flashing, has gone off, or has gone red, this indicates there may be an issue with the fibre connection coming into your property. What Can I Do? First, please check that the optical cable which comes. Customer: The power light is green, the optical light is red, and the UNI-D 1 port is orange. Unplugged and plugged in the power to reboot but still red. I've read recent posts & most have waited. Your ONT is typically located in your garage, basement or outside your home within a few feet of your home's power box.