Tonight, to my infinite satisfaction, I finally repaired my #nextcloud server.
It had been broken for a week, and every night I had dedicated several hours to trying to figure out what went wrong and how to repair it. The solution, when it came, was very simple, but finding it ultimately required that I learn more about how NextCloud and Linux work.
I pushed my understanding very, very hard, and coming to a solution makes me feel very good. I figure the people on mastodon.technology will understand! :)