Database shutdown problem

[equilibria]

On my Netgear ReadyNAS Ultra 4 Plus I had Subsonic 4.7 running perfectly for longer time.
But then out of the blue, every day at exactly 06:25 the database keeps shutting down. So I tried newer versions 4.9 and finally 5.1. But still every day at exactly 06:25 the database shuts down. What is happening? How to fix this?

The applicable lines in the log state:
Shutting down database...
Shutting down UPnP service...
Shutting down UPnP service - Done!
[Full GC 94331K->41573K(206844K), 0.8595190 secs]
Shutting down database – Done!

I tried increasing memory, but this did not help.

Can somebody help?

Greetings,
Eelco

[daneren2005]

Something in your system is shutting it down. There is no timed shutdown in Subsonic