qBittorrent official forums

An old problem,it seems (http://qbforums.shiki.hu/index.php?topic=1798.0)
Seeding works just fine while downloading (over 300 popular torrents), after completion everything (except 2-3 torrents) stops.
This happens while:
- there are connections with 5-10-15 peers per torrent
- no problem with forwarding port
- same torrents seed perfectly with utorrent.
- enabling/disabling utp management, DHT, PeX - no effect.
To be honest, I've switched back to utorrent just for this reason, though I hate lack of efficient preview playback of the latter (that works seamlessly) . There are plenty other bugs with qBit, that's for sure, but nothing that strange as this
A question : what it is all about those outgoing ports (that are disabled in Advanced settings) ?

That goes without saying, plenty of max.connections setting - 1000.

How many active torrents/downloads/uploads have you set in options? (Tools->Options..->Bittorrent->torrent queueing)

A question : what it is all about those outgoing ports (that are disabled in Advanced settings) ?

If you set a value you limit the range from which a port is being selected. ie if you set as min:1 and as max:20 then the outgoing port chosen for bittorrent will be between these values eg port 15. Don't mess with advanced settings if you don't understand exactly what they control.

Thanx for reply, those not seeding torrents weren't definitely queued , as my active torents limit was ~500, slightly higher than my total torrents number. I always verify this.
Strange problem, just right now in utorrent the same torrents are 70% active, even with just 3-5 peers connected.
Could be some sort of random discrimination from utorrent part, because 90% of all my  peers seem to use either utorrent or bittorrent ?

Is utp enabled in options? (speed tab) If not, enable it.