Apple Discussion: https://discussions.apple.com/thread/250720965?answerId=251575762022#251575762022 Most Active answer on StackOverflow: https://apple.stackexchange.com/questions/372025/missing-wifi-interface-after-upgrade-to-catalina?newreg=1904677ef3d840f0a87b73a2cd7bd342
- Download the modified files (thanks Alex!) and unzip > you get a folder named WiFi_kexts
- Boot into Recovery Mode: restart your computer while pressing and holding cmd-R
- Open > Utilities > Terminal via Menu Bar (detailed instructions here)
- Type
csrutil disable
and hit return - Type
reboot
and hit return > computer reboots normally - Open > Utilities > Terminal and enter cd and hit the space bar (don't hit return)
- Drag the folder WiFi_kexts onto the Terminal window and hit return