Networking is not my best subject
but let's have a go
Home folder on a server - I suppose you have a home folder locally as well?
This Home folder on a server - do I understand you right that you have no problems with it?
The shared folder for everyone to access, what is it called? homes? I hope so as you see a folder called "homes"
Who is the owner of that folder?
This is some kind of permissions problem where Nautilus thinks it has no rights there
Have you tried the right click option "Open as root"?
Not that I recommend you to use root but just to see what happens
You could try "fusesmb" (is in synaptic)
We had it installed by default, but it's not quite good enough to include in a LTS
Loose ends, to help me understand better....