STEP 1: Open your System Preferences window by
clicking on the Apple menu and choosing [System Preferences].
STEP 2: Select the [Network Preference] icon,
as shown in the picture below.
STEP 3: Select [Built-In Ethernet] at the top of the window.
STEP 4: Select [Using DHCP] in the [Configure] menu.
STEP 5: Click on [Apply Now] in the lower right-hand
corner of the menu.