Start by opening the System Preferences by clicking on it in the dock or choosing it from the Apple menu.
Make sure the Location drop-down menu is set to Automatic and you have selected Ethernet in the left panel.
Make sure the lock in the lower left corner is set to unlock. If not, click on the lock and you will be prompted.
If you made any of the changes above, click on the Apply button . Your new settings will take effect.
Close the Network window.