iATKOS | United Kingdom

Just got my old Atheros PCIe AR928x wireless card working with Big Sur.

Download and run the OpenCore Legacy Patcher 0.0.22 https://github.com/dortania/OpenCore-Legacy-Patcher/releases

Select option 3 Change Model. Enter iMac11,2. Press 'Enter'

Select option 1 Build OpenCore. This will build you an EFI folder and save it. At the bottom of the terminal window it will display the saved location. Copy the location.

On the Finder Menu Select 'Go' then select 'Go to Folder'. Paste the previously copied location and click 'Go'.

Select the EFI folder and navigate to the Kext folder

Copy the IO80211HighSierra.kext. Paste into your Main EFI Kext folder. You will need Clover Configurator or something similar to display your main EFI folder

Open your config plist using 'ProperTree' https://github.com/corpnewt/ProperTree . Do a Snapshot/Clean Snapshot then Save and Reboot. You will have working wifi.

Hope I haven't oversimplified this.