1. In Windows system, enter the device manager and check if there is an 'Ethernet controller' in 'Other Devices'. If so, it means that the hardware has been recognized and the driver has not been installed yet. Just install the driver;

    In Linux systems, use the lspci | grep -eth command to check whether there is a card corresponding to the chip. If so, it means that the hardware has been recognized and the driver has not been installed. Just install the driver.

2. Is the network card installed in the wrong slot (for example, the network card of the PCIe interface is installed in the PCI slot, just correct it);

3. On a multi-channel CPU server, when the CPU is not full, the network card happens to be installed in the slot that is not controlled by the CPU. At this time, it needs to be replaced with the corresponding slot of the CPU that is installed and working normally. (by changing the slot);

4. Caused by poor contact of the gold finger (the device is powered off, reinstall the board, plug and unplug the slot two or three times, and then fix the network card);

5. Plug the network card into another motherboard for testing and verification to check whether the network card is defective.