Hi Kar200,
I'm using inSSIDerOffice tools to measure Antenna bit rate, and not using speed test tool for upload and download,
By the way your image is working perfect on DIR-853 A3, and strongly recommended staff to use it, and I'll explain why I spent too much time for configure it, what is problem and how to sort it out.
Actually I have installed Freeradius 3.0 on Ubuntu Linux Server as Central Authentication Server , and my plan to integrate Router with such Server as RADIUS client,
In order to do this and as per guideline of Openwrt Forum (https://openwrt.org/docs/guide-user/network/wifi/freeradius), I have to remove preinstalled wpad-basic-wolfssl package and install wpad full package.
Once wpad-basic-wolfssl uninstalled, wireless signal disappeared completely (you can test it yourself), in addition to can't install wpad full package properly, due to getting an error that a dependency file called libubus20210603 is not available in any repository (even you can't reinstall wpad-basic-wolfssl), and I have to do hard reset in order to wireless signal to be available again.
based on your recommendation I have searched in Forum, and found that we can't install many packages due to that file and it is a bug in current 21.02.0-rc2 firmware version as per such link (Can't install dnsmasq-full, missing libubus20210603)
So the only solution is to use Use the 21.02 snapshot firmware builds, or the rc3 builds as per recommendation, and can't use one of those options without getting your help.
So you are the only one can build a custom firmware for DIR-853 router based on one of above options or both.
Thank you for your kind cooperation.