Small experiments with home networks, old laptops and quiet servers.
The X230 still boots in eleven seconds from a cheap SATA SSD. With the lid closed and the screen off it idles at about seven watts, which is less than the router next to it. Samba, a nightly rsync to a USB disk and nothing else — the fewer moving parts, the longer it keeps running.
It was the microwave. More precisely, the 2.4 GHz band in a kitchen with a microwave and three neighbours on channel 6. Moving the access point one metre and switching that room to 5 GHz fixed it. A cheap spectrum scan app would have saved me a weekend.
Key-only SSH, automatic security updates, a firewall that allows three ports, and a calendar reminder to pay the invoice. Most outages I have had were not attacks, they were expired cards and forgotten renewals.