Yes, some D-link cams have an audio format that NCS do not support. I also see that setting up the cam with a predefined template gives MJPEG as a video stream and that format do not include audio. According to the manual the cam also use h.264 compression and use rtsp for streaming which is a format that includes audio. So to test I suggest the following.
When adding the camera use Custom URL.
Set Stream type to RTSP_TCP
For URL use rtsp://username:password@ipnumber:554/live1.sdp
Usually, the Dlink have this in the configuration of the camera, but I cannot find it so this is from googling. If that do not work test:
- live1.sdp can also be play1.sdp
- remove the port number
If NCS support the audio format PCM that the cam use you should also have the sound now.
Good luck and please report back how it goes.