WiFi very slow on Tanix TX5 Pro with CE 21.0-Omega

Hi! I have an old TVBox Tanix TX5 Pro (Amlogic S905X + 2/16GB). I have now changed the old CE 9.2.8 to the latest CE 21.0 and everything works fine except WiFi. WiFi is detected and works but the transfer is very slow. The ethernet connection works fast, but I need WiFi.
WiFi on CE 9.2.8 worked flawlessly.
Any ideas?