What are you trying to do with Nextcloud? I've always found Nextcloud clunky. I personally use Immich and FileBrowser Quantum (previously just called File Browser) enough for my needs on StartOS.

Before hunting for an alternative, check if the container dies on boot: Nextcloud runs PHP + MariaDB and first launch does a lot of work, so a low-RAM Start9 will OOM it before the handshake. From the Start9 terminal, docker logs on the container and dmesg | grep -i oom will tell you. If it's RAM, S...