We have used ONVIF Server Profile S similar to the one used in this project. We have similar kind of discovery mechanism and all. Further we have implemented the apis for Profile S, like to stream video and audio in NVR Clients. Have added support for changing the video audio encoder configurations and network configurations also.
Our Server works well with Onvif Device Manager available as open source. We obtained live streaming on Onvif Device Manager and few Network Video Recorders but got a black screen( no image ) on some other NVRs while testing.
We have implemented basic APIs for supporting Streaming such as, Get Services, GetCapabilities, GetProfiles, GetVideoSources, GetStreamURI, GetVideoEncoderConfigurationOptions, GetVideoEncoderConfiguration etc.
We have verified the API calls and responses using Wireshark and observed no errors.

What are the standard methods used for debugging issues like the above.
Suggestions are highly appreciated to debug or resolve this issue