for your quick reply. I have used the Fritz!Box + ext. HDD as a NAS, which runs very reliable and stable. The OrangePi Zero Plus does only have an USB 2.0 port (with limited electrical power resources), but the Toshiba HDD is a USB 3.0 hard drive without the option to power it separately. Thus I'd like to continue using Fritz!Box+HDD as a NAS.
The OrangePi + OMV + MiniDLNA has only being implemented to provide a convenient music server, which is by far faster and more comfortable than the built-in music server of the Fritz!Box. Latter doesn't support any tags of flac-files for instance.
By this workaround I've been able to continue using Fritz!NAS, while having a nice music server (MiniDLNA) at the same time, but with very little extra energy consumption (24 x 7) for less than 30,- EUR including a good power plug adapter.