Have you try to playing connecting your computer to your router by cable? If not, do it, so you can know if its a problem that only affects your wireless connection. When you are connected by cable, if you have the same problem, try disabling the wireless network of your router.
Another thing you should check is what gets disconnected, the connection between your computer and your router or the connection between your router and your ISP. After you lose the connection, go to Control Panel »» Network and Sharing Center »» Change adapter settings (for windows 8) »» double click on the network adapter you are using and check the duration of the connection. If this duration gets reseted then the problem is either on your router, network adapter or on some other part of your computer. If this value is not reseted, you should check on your router the duration of the internet connection (between router and ISP), if this value is reseted, try to follow this steps:
Step 1 : Change Router Password, wireless network name (and you should select not to broadcast it) and key (the default key is many times easy to discover). If you have the same problem, you should try to check if your router would work properly at someone else's house, or test another router in your house.
Step 2: Make sure windows, GPU drivers, other software isn't downloading drivers/ updates.
Step 3: Make sure Steam (or similar software) games aren't downloading/ updating
Step 4: During a game minimise with Win key or Alt + Tab and check to see if Steam mods aren't downloading (The workshop likes to download while gaming)
Step 5: Ask ppl in the house if they are using the net, check devices if they are using it (relatives might be watching HD Youtube vids ect.)
Step 6: Do ping test, Speedtest to check if it isn't your ISP
Step 7: If Speed & ping is good then no one in the house is using the net.You can test here: http://www.speedmeter.de/ and http://www.speedtest.net/
Step 8: Contact ISP via email & phone and find out what is going on.
Step 9: If nothing has changed switch ISP's
(based on http://www.tomshardware.com/answers/id-2242458/high-ping-online-games-great-internet.html#13853227)