After updating Ubuntu 20.04 on my Macbook Air 2011 and MacBook Pro 2014. Wifi was no longer working. Had to copy a few packages to a usb stick.
Downloaded packages from…
Mounted the usb stick and ran the following.
apt purge bcmwl-kernel-source dpkg -i broadcom-sta-common_126.96.36.1991-12_all.deb broadcom-sta-dkms_188.8.131.521-12_all.deb broadcom-sta-source_184.108.40.2061-12_all.deb debhelper_12.10ubuntu1_all.deb module-assistant_0.11.10_all.deb reboot