Randomly loosing internet connection?

I have just bought a Lenovo g510 about two months ago. It is intel corei7, with 4gb ram and graphics card is amd Radeon. My problem is that whenever I try to download some big (like 6gb) and I keep my laptop idle, like an hour or two it just randomly looses Internet connection. On the Wi-Fi bars in the Down right corner there's a yellow triangle with an exclamation mark. And when I go to connect to my Wi-Fi it says my connection is "limited". The way I fix the problem is by turning a Wi-Fi switch off and back on (it's windows 8.1). This temporarily fixes my problem but I want a permanent solution. I searched the web for anything like this but I couldn't find any solution.

Internet connection interruption has many caused. It can be a router configuration(check the dhcp settings, etc.) or your computer network adapter driver(reinstall if needed) or your internet service provider(call them).

@tumbleweed_biff: I would considered what you said there to be correct but I have another laptop (toshiba) and I have that for like around five years now and I have downloaded loads of stuff on that laptop and this (the problem where I randomly loose internet connection) has never happened to me. Now even when I go to download anything it still goes on downloading fine without losing internet connection. So the problem is not in the router but it in the laptop (the Lenovo one)