Intel 7260 AC slow wifi

Hi,

So I have Asus G751JY ((Windows 10 x64)) gaming laptop with an Intel AC-7260 card.

I have 120 MBit/s internet connection (when i plug ethernet, the download speed is around 15MiB/s), but when I use wifi the download speed is unstable.

If i download something (for example steam games) the speed once 7MiB/s, once 4 or 2 etc.... so very unstable. I have already tried a lot of driver, but they are not solved the problem.

I have Asus RT-AC87U router with the newest firmware nad I use 5ghz, the laptop next to the router.

Sorry for my bad english.

Thanks,

Erik