If your torrents have stalled there can be multitude of reasons for this.
To solve stalled torrents commonly one of the following may have happened:
- First check that trackers are giving you peers, or that there are peers to begin with at all. Understanding how a BitTorrent swarm works can help here.
- Make sure the torrent is running and not paused or stopped.
- Check for errors for the torrent and in general (ie. out of quota, tracker(s) down etc. public trackers are notorious for unreliability)
Once you know what has happened you'll know the corrective actions. Sometimes simple torrent client restart, or stop + start the torrent may solve it, but sometimes if a open tracker or public tracker is down all you can do is wait for them to sort it out. For broader troubleshooting seeding issues, the wiki guide covers additional scenarios beyond stalled torrents.
