Keenetic Extra Dsl (KN-2111) 802.11ac changes to 802.11a while speedtesting(867mbit to 18mbit)

[gQx]

3.6.3 ver.

Before speedtest in device list my laptop is like 867mbit 802.11ac 2x2 80mhz

when speedtest starts changes between 18mbit 802.11a 1x1 20mhz  and  27mbit 802.11ac 1x1 40mhz

How to fix this?

 

[gQx]

for now changing country in home segment from united kingdom to austria works no more speed drops.