I don’t have your NAS, so I don’t know exactly what options it allows. Maybe someone else here has one that they can help you with its setup.
It’s definitely a permission problem, just confused as to why some clients can access ‘Test’ folder but some can’t. I’ll do some digging re the QNAP, something isn’t quite right with it. It seems that newly created folders within a share are not automatically being set with the same permissions as the main Share folder. I’ll see what the QNAP forums say.
Cheers
Do you have command line access to the QNAP? If you can SSH in you could try to manually set the permissions. Something like:
chmod -r 777 /path/to/Test
may fix it. But I don’t know if the QNAP would change it back.