Some unplanned downtime
Piperka went down at around 15 Jun 20:00 UTC and came back at around 16 Jun 09:00 UTC. This was totally unplanned. Apparently the server just froze, with no traces of anything in the logs. The reason why it took this long to recover from this was that I was out of town and had never committed my hosting service's web interface's password to memory. A hardware reset resolved the issue.
I wasn't going to come back home until tomorrow, but I would have hardly enjoyed my trip if I had worried about this all the time. Downtimes are a risk that I take with using a dedicated server, and with me having a day work and needing to sleep, those could last for hours. That's the name of the game, with me being my own server admin and being committed to all sorts of other stuff.
Sorry about this. At least I can say that this was the first major downtime since I moved Piperka to Hetzner, a year and half ago.