If the VDSL segment remains up and running, then most likely explanation would be some traffic management by the ISP

Reduce number of connections in torrent client.

it's down to 100 connections from 400... I would have thought the Draytek could handle 400 easily... My old netgear could handle that with Sky...

In reply to a post by MrSaffron:

If the VDSL segment remains up and running, then most likely explanation would be some traffic management by the ISP

This is what I'm presuming, but I appear to be the only one experiencing this?

It is a good point, it may be that with a faster link the router is having more problems tracking the NAT table, and falling over due to that.

Alas routers are very bad in offering diagnostics in this area, try with a small number of connections and then increase them, i.e. learn what the router can cope with.

P2P with its use of UDP and many simultaneous connections to different places on the internet is a big issue for routers, and similar at the ISP level

I'll certainly tinker, however, all I've done when moving ISP is disable WAN1 (sky) on the Draytek and enable WAN2 (vdsl)...

The entire setup is the same.

Given it's mainly linux distro's I'm torrenting (that are available via ftp etc) you could say that I can just ignore/forget about it...

But that's not me, I'm into troubleshooting and fixing these things!

400 is overkill. 100 is still pretty excessive. 25 is enough for private trackers.

Well I've fiddled with NAT settings and opted for open ports rather that forwarded ports... I've also disabled UPNP and NAT-PMP in my client.

I rattled down the latest Ubuntu at 4.3MB/s and it didn't appear to 'drop'... so we'll see how things go!