Slow WiFi

Hi Guys!

From few days I have a problem with slow Wireless connection on my R6400.

Generally my provider deliver 250Mb/s download and 20Mb/s upload, but I have on Wifi always almost 30/20Mb/s, but on cable I have maximum what my provider delivers.

It's interesting, that download speed is very regular (even if I'm 5-10 meters from router) and vary fast reaches 30Mb/s (on speedtest.net). It looks like some limit.

My settings:

Firmware Version: 1.0.1.24

MTU - 1500 and it is OK (tested)

WMI - disabled

QoS - disabled

I also tried factory reset - no change.

I greet and count on help!