This update is available for all Apple 802.11n Wi-Fi base stations including AirPort Express, AirPort Extreme, and AirPort Time Capsule. It contains fixes that:
Resolve an issue that may cause AirPort Time Capsule to report that the backup disk is in use
Resolve an issue that may cause an IPv6 Tunnel error
Resolve an issue that may intermittently cause a loss in Wi-Fi connectivity with iOS devices
Note: This firmware update is for all 802.11n AirPort base stations.
For information on the security content of this update, please visit: Apple security updates
For detailed information on AirPort base station firmware updates, including instructions how to install the update, please visit: About AirPort base station firmware updates
For more information on using AirPort products, go to the Product Support Page at: Apple - Support - AirPort + Wi-Fi