you should try zoom or bluejeans, it's been extremely stable and consistent for us, we do conference calls from behind china's great firewall to palo alto with little to no lag, even has HD video.
Zoom won't really help you with the above situation which is mainly users having their microphones disabled etc.
We're building a virtual classroom solution and we now always force every user to go through a wizard which checks their audio and video, clearly marks when there is no sound being received and connects them to a support person to help them resolve their AV issues before they can join the meeting.
It's a little annoying for the person who wants to join, but the experience for the people already in the meeting/classroom is much better.
We are currently testing with some early customers and now about to go broader. We only sell to universities though, so it's hard to demo. Here's an article with more info from one of our customers that gives you a look into the product: https://awaytolearn.iese.edu/ieses-virtual-room-online-learn...
One interesting part is that, just like in a real classroom, by default everybody is unmuted. So you can have discussions with 80 students and one or multiple teachers. This makes stuff like echo cancellation, reducing the noise floor etc. a big part of the problem we attempt to solve.
Which ISP do you use? I have friends in Beijing who use Zoom for video meetings (including screen sharing), but they still use regular phone to do the audio part, as they've found audio unreliable. (This is with China Unicom.)
China telecom at home and probably china unicom + china telecom for the office. Audio and video work fine for me, even if it's on the 4g network. Note that my company forked over money for enterprise licenses which maybe the difference here, i think the qos is a lot higher with enterprise license.
