I am having the same problem. The 8.5.x version worked fine, but when I upgraded to 8.7.1, I started having absurd freezing and lag problems. I tried downgrading to the version I had previously installed, and all it does is show black screens with the occasional flash of the camera feed. On the monitor from the NVR itself, there are no issues whatsoever, so it is purely a desktop client problem.

This is effectively no longer functioning, and I am amazed that this update has been out for a month without a fix. Black eye for Reolink, which I will no longer be recommending.