Apple has released a minor Wi-Fi firmware update for “late” 2012 Macs in the Mac App Store. Mac Wi-Fi Update 1.0 address compatibility with the 5GHz Wi-Fi band, a more modern band that offers greater signal quality and less interference than the 2.4GHz band. The update is available for free and clocks in at less than 2MB.
This update is recommended for all late 2012 Mac systems. This update improves compatibility when using the 5GHz band in Wi-Fi.
Boot ROM or SMC Version Information: To confirm the update has been applied, the CFBundleVersion string of the AirPortBrcm4311.kext will need to be checked.
New driver delivered in update: AirPortBrcm4331.kext CFBundleVersion = 612.20.15