Issues with New Teams

I have a client who are experiencing a number of issues with the new teams client

- Meetings where a combination of the old and new client versions are in use are unstable, with some users experiencing dropouts/poor call quality. 

- One user is experiencing a total dropout if he starts sharing his screen. The issue is intermittent, but has only occurred since migrating to the new client. 

- Some users are only seeing half their groups and no calendar entries after migrating.

- If the old Teams client is uninstalled, the Outlook addin is removed and it is re-installed with the new version of the Teams client. I'm not switching users to the new (sucky) version of Outlook just to resolve this issue. 

With the exception of the dropouts, I can normally resolve most issues by removing both the old and new teams clients and re-installing the new one, but this is painful and I'm not onsite with this client everyday. The only issues I've been completely unable to resolve so far are the dropouts, especially for the one user who looses connection if he shares his screen (PC is up-to-date, drivers are current etc etc) and the missing Outlook addin. Any suggestions for resolving these problems would be appreciated.  

Frankly, the quality of the new client is not on par with the old one, and if this client keeps experiencing issues I may end up moving them over to Zoom.