GX740 and D-link di-524 wifi problem

Hello everybody.
Recently i bought gx740 and after 2 days I encountered serious problem with wifi.

When i'm browsing through internet normally without downloading anything, everything seems fine, speed is perfect, pages load immediately and so on.
Everything screws up when i'm trying to download something (normally or through torrent, no diffrence in my case) or wanna watch movie on youtube or other page. My internet speed drops down so badly, that my download speed is about 1kb/s, pages stop opening and after some minutes whole wifi is disconnected...

If i close source of download (youtube, torrent client or cancel file download) everything goes back normal, wifi usually reconnects itself (or i have to reset router, btw. everyone in my home has no problem, they have regular download etc.) until i try to download something again...

I'm adding some pictures which shows ping to one site (normally fastest in my country which comes to my mind) that will visualize my problem better.
On first one you can see internet cut off after i'm trying to watch movie on youtube, on second picture i close page and everything comes back normal.

As i mentioned this problem started after 2 days, in those 2 days everything worked perfect. I installed drivers from included msi dvd, nothing else.
On my previous notebook wifi worked like a charm, i wrong now...