How do I fix a network link is down error?

1. Check if the router is connected to a power source.
2. Check that all network connections are secure.
3. Restart the router and the connected device.
4. Reinstall the device driver, if required.
5. Uninstall and reinstall the network adapter.
6. Use the Windows Network Troubleshooter.
7. Run the Ping command to check the connection.
8. Check your firewall settings.
9. Check other devices on the same network.