Reinstalling Mac mini (server?) I just got a Mac mini that I will use to play FLAC-files in my stereo (DAC to be bought). I have no idea how old it is. Might be from 2010?

The serial (on a sticker on the back of the Mac mini) is:
XSVR-106-000-R-J8m-F82-PWQ-7RJ-WHJ-L-HJ-7

However, I have problems reinstalling it. There's a sticker on the back that says: MAC OS X 10.6 SRV UNLIMITED CLIENT

The install stops after a while saying:

No packages were eligible for install. contact the software manufacturer for assistance

...I'm doing a Recovery-install from some sort of Recovery-disk and using the Internet. I'm signed into App Store etc.

These are the options I have at the recovery:



It seems like this problem could have something to do with the date?

I tried setting the date to 2017 (some sources claimed that this would to the trick) by starting in Single user mode. But I get this:
Common missing Bluetooth controller transport...

And can't even type in the terminal. Any ideas on how to restore this?
From your photo, it looks like the disk has two Recovery Partitions for different updates of 10.11 (El Capitan). 
It also looks to have an installer disk partition: like you would make for a USB stick in order to boot and install a version of MacOS.

I would select the first Recovery Partition (10.11.4), and from there launch Disk Utility and merge the other two partitions. Then install OS X from there.

If you've already tried installing from the Recovery Partition, and that's not working, then you could try Internet Recovery, which is what you do when the disk doesn't have a valid Recovery Partition. Option Command R.

Then try the same process from there: re-partition the disk and install the OS. It may install a different OS, but once it's done that, you can upgrade to whatever you like.