unplug it’s internal DOM (disk on memory - look it up)

then boot installation from USB stick of desired OS - you might have problem with fan control (old docus: https://www.cyrius.com/debian/kirkwood/qnap/ts-41x/tips/)

gmail with separate account than primary one

always put limits on containers !

i.e.

services:
    qbittorrent:
        container_name: qbittorrent
        cpus: 1
        mem_limit: 1g
        environment: