The electrical network card is recognized but not connected.

1. Check whether the network port is disabled. (For Windows, you can check the Device Manager or "Control Panel\Network and Internet\Network Connections"; for Linux systems, you can use the IP -a command to check whether the status of the network card is up.)

2. Check whether the connection of the network cable is defective (replace with a new network cable for verification test);

3. Whether the equipment at the other end is defective (including system, network port, etc.);

4. Check whether the connection rates at both ends match (generally the default is adaptive);

5. Replace the network card and check whether the individual network card is defective.