Download stops

[TwinCat]

I have two uTorrents, both 1.8.4, one in Russia (behind D-Link DIR-320), one in Germany.

First of them (on Russian side) has it's own tracker on, seeds 1.34 GB file, necessary port is opened.

The download is performed at acceptable speed (ca 100 kbit/s) but it downgrades in 1...5 minutes to zero although the torrent is not stopped. If I restart downloading immediately, it resumes but after 1...5 minutes downgrades again.

Played with bt.use_ban_ratio parameters and with encryption options with no result.

The problem arises regardless of whether I'm trying to connect purely over Internet or through VPN using local IP adresses.

Please guide me to help to find where the problem lies.

Update: other computer on the German site downloads without interruptions.

[Switeck]

Seeds/Peers having instantaneous disconnects?

Or remain connected but give nothing?

[TwinCat]

They remain connected but give nothing.

[Switeck]

Either of them using uTP or Teredo/IPv6?

100 kbit/s is only about 12 KiloBYTES/second. uTorrent displays speeds in KiloBYTES/second.

[TwinCat]

Neither of them uses Teredo/IPv6.

I don't know whether they use µTP. How to be sure?

> uTorrent displays speeds in KiloBYTES/second.

Ok, 100 KiloBYTES/second.

But displayed download speeds of 1...1,5 MB/s are typical for me, although I have a 4 MBit/s channel. (1MByte/s*8=8MBit/s).