We've been successfully using vMix and Restream for at least a year at our small church. Today, early in the service, an error message I had never seen. Restream telling me the Keyframe Frequency was too high (6 instead of 2). That setting is not available in Restream, so I looked in vMix. I could see most of the configuration in Streaming settings, but places where something might be changed were non-responsive. I assume because the streaming was live. I enabled the Record button so we would have at least a clean local copy of the video.
After the service, I was able to open the vMix Stream configurations, and Keyframe was normal at 2 sec.

So if vMix was sending a normal Keyframe Frequency, could something else change that?
A local technology company was in the church this past week, but only to measure account settings.

I'm stumped.