internet stops working after a short bit

So I was wondering if any of you knew what to do. My computer has internet at full speed for maybe 10 minutes and then drops to almost nothing. It only does this after restarting my computer otherwise its always really slow. I have my phone running off of the wifi and my xbox is wired just like my computer and they both are fine so I figure it has to be an actual computer issue but I just don't know what is the problem. Help?

Could be a bad cable or port in your router that may be acting up. Are you trying to run your computer, phone, and Xbox all at the same time? If you are, all of that traffic would lead to a slow down. Hmm...don't really know what to say though about it only happening on restart.

I switched cables and still the same thing. And not at the same time, I'm only trying one at a time and everything seems to work fine except my computers connection. And the cord I'm using now I tested on my xbox and it worked fine too.

Hmm...well then the next thing to test for would be a faulty network card.

Edit:
Actually, I should've asked you these questions before but...
1)What EXACTLY do you mean "stops working/slow down"?
2)Do you have a lot of programs on your computer running during this slow down?

Do the usual stuff to make sure your computer is not overheating - i.e., open it up, clean the dust out, and make sure all the fans are working.

If that doesn't help, you may simply have a bad component, which would be hard to pin down through forum posts. If you have a separate LAN adapter (not common these days), you could try replacing it. If you have on-board LAN (more common), and cleaning the crap out of the chipset heatsink/fan doesn't help, my next step would be to try another motherboard (which is not easy, if you don't have a spare. )