I checked, guest has ‘No access’ for Movie, Music and Photo. I’ve granted read access to Guest for /volume2/Movie, but still not able to access from OSMC, however the /volume2/Music and /volume2/Photo are accessable from the OSMC.
I realised some interesting things on my Synology (some irrelevant lines are removed):
bash-4.3# ls -l /volume2/
total 0
d---------+ 1 root root 98 Jan 1 17:15 Movie
drwxrwxrwx 1 root root 306 Dec 23 20:17 Music
drwxrwxrwx 1 root root 168 Dec 23 19:33 Photo
bash-4.3#
Shared folder ‘Movie’ has different OS level rights than Music and Photo. Could be this the issue?