If the indicator light is on at one end but off at the other, swap the fiber jumpers at both ends. An optical module is a critical component in modern optical communication systems, directly affecting transmission stability, network reliability, and operational efficiency. However, during installation and daily operation, various issues may arise. Therefore, understanding common optical module. Check the model of the faulty optical module. Cause 2: The type of optical jumper used does not match the optical. Based on typical issues encountered with optical modules in daily switch applications, this document summarizes basic troubleshooting steps for resolving common faults: 1.