/etc/modprobe.d/brcmfmac.conf/options brcmfmac feature_disable=0x82000
Will fix problem with above wifi system on imacs.
What problems are you referring to?
Does not connect, rejects log-in Password. One solution was a little convoluted and involved disabling wpa_supplicant and replacing it with iwd etc. Adding the above to modprobe.d is far simpler.