After 3 years of struggling with my MBLD I bought myself a Synology DS214+.
i in totally spend probably about 30 days of searching, trying, cursing, waiting, to solve all the problems. It did not want to go to sleep for 1 year, both disks crashed, the system broke down (WD did an excellent job in recovering my data and sending me a new (repaired) MBLD, chapeau for that!). It disconnected all the time, could not reach it via the user interface. Time machine backup was corrupt. Rebooting was standard procedure. Datatransfer was slow, etc, etc
I installed both WD 2Tb disks in my new Synology and spend 2 hours to set it up. Everything works!
WD makes very good drives (still in use), but should stay away from a more complex challenge.
I thank you all for the support you gave me, and wish you all better luck with your MBLD!