D-Link Wireless AC1200 User Manual page 25

Section 3 - Configuration
Step 4
You will see the Welcome screen. Tap Start to proceed. When the
Operation Mode screen appears, tap Next.
Step 5
At this point, make sure that your router is connected to a modem. Plug
one end of the provided Ethernet cable into your DSL or cable modem,
and plug the other end into the port marked INTERNET on the DIR-850L.
Tap Next to automatically detect your Internet connection and proceed
to the next step.
D-Link DIR-850L User Manual 20