> completely frozen, need to shut down and restart.
I'd check to see "how" frozen it is: e.g. try to log into it via SSH (or
better yet, keep an `ssh` or `mosh` connection to it with an `atop` or
`top` running inside of it, and/or `journalctl -f` so when it freezes
you can immediately see if the remote connection is also frozen and
what it is/was doing).
Stefan