Slow internet on only one computer?

[Marokkino]

I have a 60mbps subscription at bright house network and a router Zyxel zywall USG20. My internet speed is just fine expect on one computer, my gaming desktop (of course).
Whenever i try to accomplish bandwidth-consuming tasks such as downloading, watching a video on youtube, try to find game servers, my download speed drops from 20mbps to 20kbps. If I'm lucky, i will be able to quickly launch a game at my computer startup, find a game and play with a good ping all the way, but if the game were to crash and I tried to relaunch it, I wont be able to to anything, including surfing, at a speed over 30kbps. So I opened my router panel and found out that the connect rate of my computer is ridiculously low compared to every other devices.
By the way, I can watch videos just fine and download at 2mbps on all my other devices.

Screenshot of my router panel: http://gyazo.com/d54b4934885aca9f6ef0ee945d7dbb6e

I would be thankful to anyone who has a mere idea of what is happening.

[Lawrence]

Try wiring the device directly to the modem without it going through the router