Frequent, disruptive crashes
So as a developer I realize this is a huge vague problem and you need details, but not sure what details would be helpful...
I am hosting a weekly game on an Ultimate version on a Mac.
All my players are on the demo version, all on PCs except for one, (we have 7 total)
Invariably ... every week ... we'll have 1-3 players who have to shut down, quit process, or otherwise restart their game before they are able to:
A) Connect at all: the server says Soandso connecting ... Soandso dropped over and over... (this while others have connected just fine)
B) View a map: I share a map and some players see it and it loads just fine, others get the "Image of Doom" where they get all kinds of loading errors and have to restart the app.
C) Get their game to stop crashing: Sometimes instead of just B, they get the "Superior Image of Doom" The description for that item is: "Once per long rest causes you to no longer be able to connect to the server, or in the odd case that you do, cause the image to crash your game. The only solution to this is to roll a DC 15 Intelligence saving throw, and blow away your game cache"
Lets see, what else...
We're playing D&D 5e and I have all the primary books (though not all adventures) but the content we're running is custom.
I wouldn't know what else would be relevant.