Go to "System" > "Preferences" > "Network Connections"

Under „Network Connections“, you should have wired connection (usually called "auto eth0").
Select "auto eth0" and click on „Edit“

Make sure that the following checkboxes are checked:
Next, click on the „IPv4 Settings“ tab.
Under „IPv4 Settings“, choose „Automatic (DHCP)“ from the "Method:"
dropdown menu, then click "Apply".