If the transceiver is not recognized by the switch or link errors occur, unplug and reinsert the transceiver, then confirm that it is correctly inserted into the designated device port.

Please perform the following checks to verify the possible problem:

• Check whether the types, data rates, and wavelengths of the transceivers at both ends are identical.
• Check whether the data rate, working mode, FEC function, and auto-negotiation mode of the ports are identical.
• Check whether the connected fiber optic cables or Ethernet patch cables match the transceiver.

Log in to the management interface of the connected device and check whether an error message appears after the module is inserted. If there is an error message, the transceiver may be faulty or incompatible with the device.

Check the DDM information of the transceiver on the current port and confirm whether voltage, current, temperature, RX power, and TX power are normal.

Note: DDM is not available for Copper RJ45 transceivers and converter modules.

Check whether the port light connected to the transceiver is normal. If not, perform the following checks:

• Repeat the test after cleaning the TX port of the module and the end face of the fiber cable.
• Check whether link loss is within the transceiver power budget.
• Calculate the budget by subtracting the minimum receiver sensitivity from the transceiver TX power.
• Repeat the test after inserting the module into another known working port.
• Repeat the test after replacing the cable with a known working optical cable.
• Repeat the test after replacing the module with another transceiver of the same P/N from the same FS order.