Using Onvif device manager on my camera, I get a “No Signal” when trying to view Live video on the main stream. However, if I switch to the substream profile, I receive the signal correctly.
Often, this is because the camera is set to H.265 video codec. Onvif Device Manager does not support this newer codec. I guess the substream is set to H.264. This is why the substream works, but not the mainstream.
To change the stream to H265, you have to connect to the camera from a web browser and modify the video configuration.