unable to add a (NAS) new directory to the Music Library

I’ve bought a new NAS Synology DS-220+.

I want it to be a source for my Sonos Music Libray.

When i want to add the path to a folder of this new NAS, i receive a “error message 900”.

I precisely executed the instructions found on the Sonos support site (IRPStackSize).

It doesn’t work.

any idea ?

(Please note that if i try to add a folder on my old NAS, it works fine !)