As of 27 Nov, 2020 I was able to resolve Wi-Fi connectivity issue after upgrading to Big Sur 11.0.1 by resetting NVRAM What you need to do is shut down your mac and immediately after you turn it back on, simply press and hold on the following keys simultaneously for ~20sec, then release the keys and proceed with login to the OS, hope this will help you too. Option + Command + P + R