no longer able to transfer flac music files to my NAS

[BlueDog]

Of course, SMBv1 support can currently still be re-enabled (see here) in Win10 but there's no guarantee that M$ won't remove that capability altogether in a future update release - the top and bottom of it is that the protocol is insecure and needs to be killed off.

The OP might find it worthwhile asking on the Vortexbox forum, maybe there's a firmware update available for the unit to address this issue...