samba could actually be reserved. Try making a different group with a different name and adding the users to that.
While this worked (the correct ownership seems to be showing as far as I can tell in the GUI), I still get the permission error message.
Hey, a short update on the speed thing. I tried to transfer a folder with a few larger files (GOG game setup files) from one Windows PC to another through the Homegroup-system. This peaked out at 74 MB/s transfer speeds. A significant difference in speed.
Have you tried restarting the samba service? I'm not really sure why it's not working.
Yes, I restart the service after each change to the smb.conf file.
Sorry for the delay.