My wifi is only weak for my pc.

[Akhmed]

I've always had problems with my wifi/internet connection, it has always been weak, and only for my pc.
I had a €60 powerline adapter untill a week ago, it works good for the first 5-15 minutes that it's been plugged in, after that I start lagging very hard. I had to re-plug it in for another 5-15 minutes of good internet connection.

A week ago I decided to buy the "Asus USB-AC68" wifi adapter and my wifi is still weak, I lag in every game that I play. For my browser and stuff it works fine most of the time.
Why is my wifi still weak? My setup is next to my brothers setup and for him everything I used works just fine for him and he doesn't lag with my wifi adapter, I don't understand why it's working good for his pc (which is a lowbudget pc), and is weak for my pc.
My wifi often disconnects and reconnects (while in-game and only for me)

My wifi router is one floor below me.

If it helps, here is my setup:

GPU :2x MSI GTX 960 (SLI)
CPU : I7 4790k @4ghz (Overclock @4.4ghz)
CASE : NZXT H440 Limited Edition - Hyper Beast
RAM : 16gb Corsair Vengeance
MOBO : ASRock z97 Extreme6
PSU : Corsair RM850 (850W)
SSD : Samsung 850 EVO 250GB
WIFI Adapter : Asus USB-AC68

 

[NOT_PROVIDED_16]

how about a wireless range extender?
something like this: http://bit.ly/2e1Dx1X

I use the TL-WA850RE and i can't fault it.

 

[JohnnyBoy05]

Go to Speedtest.net and tell us the results on both devices