Hibernate / sleep Synology 214play

[RuudS]

I run MinimServer on a Synology 214Play. Some weeks ago I saw that this NAS doesn't go to hibernate state any more (not even after a few days). Until some weeks ago it did.
I stopped all services and after a restart it went (after 10 minutes, as set) into hibernate state. After I restarted the most important app on my NAS: Minimserver (and therefore Java) the problem was here again. To me it looks like an update (in Minimserver, Java and/or DSM) prevents the NAS (HDD) go into sleeping mode.

As far as I know and remember I didn't change settings that could be of influence on this. And now I checked, all seems as should be.

I can't find any link with changes. The only thing is that a power failure occurred the same day the log indicates a repeated: wake from hibernate. I haven't been able to find out what caused the wake.

What can I do to solve this?