Torrent problem - uTP

[derrida 0]

I'm under Windows 10 Pro, Eddie Client 2.10, 20/1 Mb ADSL line.
I'm using latest qBittorrent.

VPN works great, http/ftp downloads saturate download/upload bandwidth.
Torrenting is a bit problematic: it reaches a 10-12 Mb wall in "testbench condition" (ubuntu torrent), about the half with "real life" torrent.
I know for sure the same torrents have no problem at all outside VPN tunnel.

What I've just tried (with no luck):

- differnt VPN servers/torrent client;
- port forwarding;
- setting mtu;
- changing send/receive buffer size;
- downgrading TAP driver;
- forcing UDP protocol/SSH/SSL.

What worked (in some way):
- disabling uTP.

By disabling uTP, speed bumps up with testbench torrent but less peers are gathered (I guess this happen because uTP is very common/efficient protocol) so "real life" torrent speed is not great at all.
Furthermore, with uTP disabled, the connection status icon remains yellow and turns green only if uTP is enabled.

Is this a common issue? Am I missing something? Is there a way to let the VPN handle uTP?