I upgraded to the latest waydroid images and faced the same issue. Executing sudo sed -i '/aidl/s/2/3/' /etc/gbinder.d/anbox.conf after making rootfs writable did solve it. (like described in the thread posted above)

@th0mas Have a look here for all you need https://forums.ubports.com/topic/3229/sony-xperia-x-suzu-f5121/37

Thanks for the help. I have tried that, it is a little bit better but not very good. I have also tried to install the latest LineageOS and the WIFI works flawlessly. So it is not a hardware issue. Enabling only 2.4GHz Wifi does not help.