I download any torrent. It will seed while downloading. After download is complete file will not seed? Continually tries to connect but all connections time out. Using an xfinity wifi hotspot?

If you are talking peer connections it could just be the peers are not setup for inbound connections, which would require them to connect to you, and if you're not setup for inbound connections then you two cannot connect to each other.

And being on a "hotspot" means you would not have any ports forwarded to you, thus no inbound connections.