Archer C6 wifi problems

Hi! I have recently installed OpenWRT on my TP-link Archer C6 V2 and my wifi is not working proprely. When im connected by cable i got 500Mb/s but when im using WIFI 2.4GHz i can't reach 50Mb/s
Firmware Version:
OpenWrt 19.07.2 r10947-65030d81f3 / LuCI openwrt-19.07 branch git-20.057.55219-13dd17f

What is the output of uci export network; uci export wireless
Are you using the same PC to test speed in both scenarios?
Are you close to the router when testing with wifi?
Are you living a densely populated area, like a block of flats in a city or some rural area with family houses around you?
Have you scanned for interference in the spectrum with some application on the phone?