I am one of those people that "Back to My Mac" never worked for. I checked the (minimal) Apple support documents, asked around, searched forums, and tried about a dozen things and never figured out what was wrong. Today it started working again because of something I did and I figured I would post about it both because I never heard of it before, and in case it affects anyone else.
It turns out that in the .Mac preference pane, on the "sync" tab, in the (hidden) "Advanced" sub-section ... you can see a list of computers that have ever attempted to sync to the .Mac service. I didn't notice this list as I wasn't really using any of the sync services myself, just the "Back to My Mac" part. Although (and this is *key*), I did experiment with syncing when I first installed Leopard.
It turns out that when if you *ever* use the sync services, the name of the computer you tried to sync from is held in a list on this tab. If you then change the name of that computer, (I did) then a new entry is made for the new name, but it never clears the old entry.
Entries are automatically added to this list without your knowledge every time you sync a computer with .Mac and cannot be cleared until you actively select them and click "OK" to a scary poorly worded dialogue. You also have to re-boot the computer.
Until this hidden list is cleared of these "bogus" entries, the Back to My Mac service will never, ever, work. As soon as I (manually) cleared the list of the imaginary computers, "Back to My Mac" worked like a charm.
It turns out that in the .Mac preference pane, on the "sync" tab, in the (hidden) "Advanced" sub-section ... you can see a list of computers that have ever attempted to sync to the .Mac service. I didn't notice this list as I wasn't really using any of the sync services myself, just the "Back to My Mac" part. Although (and this is *key*), I did experiment with syncing when I first installed Leopard.
It turns out that when if you *ever* use the sync services, the name of the computer you tried to sync from is held in a list on this tab. If you then change the name of that computer, (I did) then a new entry is made for the new name, but it never clears the old entry.
Entries are automatically added to this list without your knowledge every time you sync a computer with .Mac and cannot be cleared until you actively select them and click "OK" to a scary poorly worded dialogue. You also have to re-boot the computer.
Until this hidden list is cleared of these "bogus" entries, the Back to My Mac service will never, ever, work. As soon as I (manually) cleared the list of the imaginary computers, "Back to My Mac" worked like a charm.