ssh only after a reboot doesn’t solve the problem, of course

Yeah I’m pretty sure a raspi 4 is up to the task. I ran a 512 GB jellyfin server on a raspi 3 for a few months, and the only issue was with transcoding video/audio (raspi doesn’t have the right hardware acceleration for that).

Never used nextcloud, but yeah you’ll probably want to update to 64-bit raspi os

Raspbian (modified Debian Jesse) on a raspberry pi 2B (which I am still using over a decade later to host some discord bots). Also now using Debian 1Bookworm on an old optiplex as a media server.