If the LOS light on your fiber router or ONT is blinking red, it usually means Loss Of Signal. This guide explains the likely causes, the checks you can do at home, and when the issue needs technician support. Existing Krishii Fiber customers can share their registered mobile number, area and a. 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. It often indicates that something is wrong with your internet connection or the device itself. When there is a signal, the red LED does not blink and does not light up. Of course, specialists from the company from which I got the service were called.