Well, I can see that a few other users have reported the issue, most with ADSL and low UL (maybe this is the case the issue manifests itself more) . What I can suggest for you is to try the same configuration (I'll email you my dat files) and focus on low UL limit (~10-15K). Make sure you measure with some external tool . AS for the test conditions: 2 DL tasks and one seeding task with ~3-4 slots was enough to cause it. Make sure you have a popular torrents (~1000+ peers). It was no effort at all to "break" the DL limit. with the UL limit - it was more "difficult" to see it on the speed graph, but you could see it easily with an external tool. I guess we can count on the the report you had in the 1.8.3 thread that with TCP it performed good, but you are more interested in uTP , right ? ... I can only point out one more thing, that in my case - I am behind a NAT and had to change the external IP with my ISP ( actually switch to another ISP) a few times during the download. Maybe it is related. good luck!