hi Axron,
Okay frist of all this at first glance sounds like ISP throttling thats gone haywire.. but you do say its only on a one to one connection. So.. first of all im not sure your understanding about the bandwidth throttle.. i think your speaking of the right click option .. so your throttles must have a limit set in Outgoing..
Im not sure how you set up your outgoing bandwidth throttle but just for shits and giggles .. Id like you to go to this page with WinMX off
https://www.winmxworld.com/scripts/bandwidth/Let the test run and set your Outgoing bandwidth throttles according to its recommendations.
Then I'd like you to not mess with the settings of the right click throttles and see what happens. If your still having issues come by the help room and talk to one of us there.. with DSL. Give them the link to this post if you dont want to try to explain again. And lets do a test with known working.. configured DSL users to rule out.
WinMXWorld.com Help_E3D7EFD5BABE
I for one know that ISPs when they are throttling p2p usage always pick on WinMX, they also can have certain users on certain ISPs that they have no problems with and most others are complete crap.. so what your saying doesnt make you crazy.. but actually finding a reason could make you wish you were.. lol
Come by the room if you want and we'll see if anything flags up..