After upgrading to 2mb/s from a 1mb/s connection on a premier account my bittorrent speeds have suffered. Before I could get 110kb/s and now I can't access anything above 30kb/s even though all the correct ports are forwarded. After reading around on the forums I have heard that plusnet are capping download speeds on p2p. Is this happening on all the different type of accounts and is this true? Would this explain my connection problem?
Plus Net don't cap any connections, but they do operate traffic shaping during peak hours. This does affect P2P traffic, and will result in some slow down during peak hours, which are 4:30pm - 12:00am (I think that's correct).
It's also possible that your exchange has an issue, and finally depending on the quality of your line, if you got 2Mb by the skin of your teeth. It could be that at times it goes over that limit and your connection suffers as a result.