I have tried:
1. having all callers and host on headsets. No external speakers.
2. Routing callers on same bus A audio return to them, host on master then on separate bus B
3. Routing everyone on master, everyone can hear everyone, but callers have echo.
4. reducing volume, which made it harder for callers to hear.
5. Tried various audio VST3 64bit plugins.
6. I've tried various settings on my Mackie ProFx12 mixer.

I had callers switch to Zoom and had no echo and audio was great. I'm now using Zoom until I can resolve the echo. I've searched all the Vmix Caller "echo" comments.

I've even PM individual with the same problem with no one responding.

This seems to be an audio loop from an external speaker or routing that is looping internally. I've dealt with audio echos before and was able to resolve them. But the Vmix Caller can't make it work without echo for the callers.

I'm sure its just something simple I'm missing. But getting desperate.