D-Link AC750 User Manual page 17

Section 3 - Configuration
If the router does not detect a valid Ethernet connection from the
Internet port, this screen will appear. Check the connection between
your broadband modem to the Internet port and then click Try.Again.
If the router detects an Ethernet connection but does not detect the type
of Internet connection you have, this screen will appear. Click Guide.me.
through.the.Internet.Connection.Settings to display a list of connection
types to choose from.
Select your Internet connection type and click Next to continue.
D-Link DIR-810L User Manual 13