This could also be a sign of improper port forwarding settings on your network. See, you need to make sure that the port that your torrent client uses is forwarded in your router to your computer, both in TCP and UDP. This is a rather critical step to ensure that you can properly receive incoming connections. While you may be able to still seed on some trackers, even as a passive node, this is something that is very difficult to do with our system.
So… You need to make sure that the proper port forwarding settings are in place.