You and me are having very similar issues. Take a look at this thread and see if your issue seems similar: https://forums.plex.tv/t/pms-v1-18-1-2019-crashed-2-times-in-3-days-win10
Mind you, I was having “crashing” almost daily on earlier versions, and had it mostly fixed by the 2171 release. I’m still seeing the issue occasionally, but nothing like before.
You should check to see if the PlexMediaServer.exe process is actually crashing, or actually just hanging. In my case Plex would continue to run, but would become unresponsive for up to 45 minutes at a time, eventually fixing itself without intervention. If your situation matches up with mine, then it would be great if you could submit logs and a process dump to the team as outlined in the thread I linked.