Those poor customers whose internet providers moved them behind a NAT face an outgoing connection issue fro torrents.
Open ports whatever you want, you can’t really do much – ISP’s NAT is beyond your control. While you still can download torrents, uploading is out of the question, which is bad for your ratings. However I accidentally came across a port number 63222, which changed the yellow triangle in uTorrent to a green tick, and the app started to upload! I don’t if it this port or just a local peer which suddenly appeared, but torrents stated to upload when connect through all of the 3 ISPs available for me, including a mobile one.