Blizzard see below
Assign a community manager.
Ask your player base for help as private contractors. Some of us have 20+ years IT/Networking experience. Just have them sign a NDA/Non-compete if that’s the worry.
The original D2 didn’t have these issues, it is something you introduced with programming/server setup.
Considering the re-release wasn’t free there should be a lot better line of communication and at the very least a roadmap on how problems,bugs,issues are planned to be addressed.
Also a forum/community manager would help to categorize the issues and eliminate duplicates to help narrow down key areas.