Torrents works well now, download is fast.
I still don't get it: my own test (from another Seedbox) hasn't downloaded anything after an hour.
Is is normal that only one tracker returns 'success' and peers data?
That's probably not good, but I'm not sure how to change to fix it.
I (arbitrarily) selected those trackers:
udp://tracker.opentrackr.org:1337/announce
udp://denis.stalker.h3q.com:6969/announce
udp://opentracker.i2p.rocks:6969/announce
udp://tracker.internetwarriors.net:1337/announce
udp://tracker.coppersurfer.tk:6969/announce
And indeed, only the first one seems to recognize the torrent.