I had a similar issue, one of the services didn't stop and the patch install timed out. I opened a ticket and they said I can stop all services except LabMySQL and run the patch again. This worked for me, though YMMV. I did not have an inoperable server after the patch failing to install, so it's likely you had a different problem. I've been running 2020.11 for about a week now, it seems to be stable for us.