Hey just so you know there are a ton of people having these same issues. Unfortunately Blizzard is ignoring us. It’s very validating to see someone not only having very high end hardware but both issues at the same time. Here are the main threads concerning these issues:
The crashing issue: Game constantly crashes since the new season (11) dropped - #13 by Lilith-12907
The disconnection issue: Servers keep crashing (Season 11) *Battle.net problem?