Wifi speed decreased twice in LAN after upgrading to El Capitan

Hi,

I have a router Asus RT-AC68U. All connections via cable are 1000mb. With Yosemite I got about 400-500mbit via WiFi inside of my LAN network. Looks like it is max for my Macbook Pro 2014.

After upgrading to El Capitan I have about 150-200mbit with the same devices with the same files with the save WiFi network.

Tried to revert to Yosemite to check. Yes, Yosemite gives 400-500mbit, El Capitan gives 150-200mbit.

How is it possible? Is anybody else can check it?