D-Link AC750 User Manual page 23

Section 3 - Usage
7. You can now use the mydlink SharePort app interface to
stream media and access files stored on your removable drive.
The wireless icon at the bottom will be lit blue to indicate
a Local Access connection. It will be green to indicate you
are connected to the router through Remote Access.
Note: If you see a red wireless icon, your router's network environment may not
be suitable for a direct network connection and you may experience slow
network speeds.
D-Link DIR-510L User Manual 19