Connection shuts down

[Spacc]

So, last hope.

When I start Vuze and start donwloading my internet shuts down and this only happens with Vuze, browser downloads do work fine.

When I start it hits top speed in no-time but after half a minute to 2 minutes it hits 0 and all my internet is gone.

I've already tried a lot of things, like limiting the connections etc. 
It did improve a little when I shut down my firewalls inside my router, but my internet still shuts down.
I also did forward a port.
I always have the green face so that's all good.
I have all the recomended settings.
I have good torrents, as I said it reaches top speed in no-time.
I work on a Macbook Pro and a IMac, both don't work.
Sometimes the whole network goes down, sometime only the one computer.

I've really already tried a lot, so you're all my last hope.

Thanks!

Spacc

 

[Jabberwok]

is the same for me, it starts good but after 10 seconds i heard a strange sound and then the downloads go to 0