My broadband has always been ADSL and I have always used the router supplied by the ISP, whichever the one of the year is. These routers never let me browse while I am downloading torrents. Web pages will eventually display but the browser's response is glacial. Meanwhile the torrents are going fast - it isn't traffic shaping. I have experimented with the torrent client settings of course and used different clients. It doesn't make a difference. It is the same whatever computer I use and if one or more torrents are running at as much as 20% of my broadband's capacity on one computer, internet use on that and other computers, wifi or ethernet, is affected. The more simultaneous torrents, the more and earlier the effect happens. I think it can only be the router. It is not an upload or download bandwith issue. I have monitored both, and limited them in the torrent clients.
What reasonably cheap ADSL routers cope well with torrenting? I will probably go to fibre this year. Will I have the same problem do you think?