Well, there's the difference between 'unread since last visit
' and 'unread
'. The link on the forum typically shows 'unread since last visit', so if you then change device you'll probably be logged out and in again, resulting in a new visit. Hence no (or very little) posts since last visit.
When I have no more 'unread since last visit' posts, I usually get the option to 'show all unread', which is what I prefer anyhow. Perhaps you could visit http://forum.vectorlinux.com/index.php?action=unread;all
instead of your normal link. I have that page bookmarked for easy access on my computers.