Why does my pc keep disconnecting from Wi-Fi?

So i have a lenovo y500 with dual gt650m
it runs really well except that i have problems with my Wi-Fi… I connect to an airport extreme that goes via a linksys adsl2+ modem to the wall… I don't think it is a problem with my Wi-Fi card since it runs well on my schools Wi-Fi and when i use hotspot from my phone. Could anyone help me with this. I read somewhere that disabling ipv6 would get rid of this problem. My antivirus doesn't find any viruses or malware so i don't think it is because of that reason.

IRQ sharing problem? When OS was reinstalled it messed with the MOBO drivers or the modem drivers. Find out who made the MOBO (get the ID off the board) and check the manufacturers website for updated drivers. Also I'd suggest disabling IRQ hogs by accessing the BIOS before Windows boots and turning off used serial ports, etc.

Sounds like you can check if your wireless network is 5GHz frequencies, because it's incompatible for some devices. You can try to switch your router to 2.4 GHz, and you can check more detail from here, http://www.mywifirouter.me/blog/new-wifi-technology-by-fcc-provides-high-speed-wifi/

I have had problems the same as you. My problem was my home router. And I found that the less expensive router models tend to have weaker signals and often drop the connection when they get "pushed to their limit" by a fast internet connection and system demanding lots of bandwidth.

What I did that fixed my problem was I researched what was the best router (speed, throughput, stability, etc…) within my budget was, and upgraded my router.

Is it your computer or is your internet? Call your internet company and if there's no issue with your internet then take it to a computer shop?