I have already 3 Q10 Pro with Android 5 and all work fine with my QNAP TS-453A. It was easy to set those up.

Last year I successfully upgraded all 3 to Android 7 but after having encountered issues like not all 8TB hard drives could be recognized, I successfully downgraded them back to Android 5 - thanks to the Futeko instructions.
Here is the issue:
I just received a Q10 Pro from Futeko with Android 7 and Firmware 2.0.9. After having spent hours reading in the forum and trying different things. But from the media center I still haven't been able to access all 4 HDDs in the NAS. I can only access the files from one HDD but much slower than on the Android 5 units. I get error messages like "new server error" or "network error please check network state" or "password not valid". That makes no sense as I simply swapped a functioning Android 5 Q10 Pro with the new Android 7 Q10 Pro and applied the same password.
So I tried Kodi and I could access all my files (mainly movies) on the NAS. But then I had unexpected issues with the wrapper.
That very much reminded me of my bad experience last year with Android 7. So I wanted to downgrade my new unit to Android 5, following the instructions and download links given in this Forum and the same way as I had done it lasdt year: I pressed and held the pinhole UPGRADE button on the back of Q10 Pro, then I turned on the Q10 Pro and once I saw the Android 7 colored circle upgrade logo I released the UPGRADE button and waited until the Himedia homescreen appeared. Unfortunately it showed still Android 7 and 2.0.9.
So I tried an upgrade to 2.1.0 but the result was the same.
I am tired of Android 7 and would like to downgrade to Android 5. For some reason it does not work. Any suggestions from you guys?
As a last option I will return the unit to Futeko within 30 days and look for something else...