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_6.30.223.271-12_all.deb broadcom-sta-dkms_6.30.223.271-12_all.deb broadcom-sta-source_6.30.223.271-12_all.deb debhelper_12.10ubuntu1_all.deb module-assistant_0.11.10_all.deb