I have the same issues when testing Wyse 5070 running ThinOS 9.1. Sound disappearing for a few seconds in Teams. Youtube sound is very bad, and other issues as well. In my opinion ThinOS 9.1 is not quite ready for rollout in a production environment. I have downgraded the Wyse 5070s from ThinOS 9.1 to 8.5 and are running them on Teams 32 bit. Works much better.