If the optical indicator turns red or blinks, it indicates that the optical fiber signal cannot be received, usually due to the following conditions: [1] The optical interface of the optical cat is faulty, and the optical cat needs to be replaced. [2] The indoor pigtail connection optical cat connector is loose, plug the connector can be restored; [3] Some indoor optical fibers are excessively bent. Excessive bending of the optical fiber will affect the total reflection transmission of the optical signal in the optical fiber, so long as the optical fiber is straight; [4] If some outdoor optical fibers are broken or the optical port of the equipment room is faulty, contact the staff for troubleshooting.