Looking at the journalctl output, I don't see any messages indicating the cause of the failure leading to reboot. It looks like it can take as much as half an hour for the system to come back up again.
I do see a large number of messages like this:
There are also a lot of these:alsactl: /usr/sbin/alsactl: set_control:1325: failed to obtain info for control #45 (No such file or directory)
I'd like to clean up my boot process as much as possible. What are these messages and how to I fix/remove them?Oct 01 19:17:01 n2c CRON: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Oct 01 19:17:01 n2c CRON: pam_unix(cron:session): session opened for user root by (uid=0)
Oct 01 18:17:01 n2c CRON: pam_unix(cron:session): session closed for user root