Sorry,
I have this quite common issue I can see, but every reason seems to be different.
Every few days, randomly you suddenly cannot connect to server, dockers are down also without warning. Cannot SSH to it, cannot see it on network. Disks are not running, but the fans are. Hard reset is needed every time.
Syslog shows nothing (nchan process is just mobile application to check the array):
It started after boot USB started failing and I changed it for the smallest I could find 16gb, but still USB 3.0. There are no other failures.
I checked the hardware, PSU etc. Didnt do memcheck yet.
Not sure, should I try physically connect screen and keyboard to see if it is IP related, or does it really freezes without warning. Never had it before.