A number of users on Apple’s support forums noticed that the latest Airport/Time Capsule 7.6.3 firmware released last week seems to disable IPv6 tunneling on various devices. It isn’t a big surprise to many users that have experienced the functionality being disabled with past versions of the firmware, and it will likely be fixed in a future release. You can revert to a previous version of the firmware until Apple fixes the issue by using the instructions below:

AirPort Utility 5

  1. Open AirPort Utility.
  2. Select your base station and choose Manual Setup, or double-click on the Wi-Fi base station icon.
  3. Choose Base Station > Upload Firmware…
  4. From the window that appears, select a firmware version and click OK. If you select Other from the Upload Version menu, you will be prompted to manually locate the firmware update.

AirPort Utility 6

  1. Open AirPort Utility.
  2. Select the base station you want to downgrade.
  3. Place the mouse cursor over the version number and hold down the Option key to turn it into a pop-up menu. Press and hold the mouse button to open the menu.
  4. From the menu that appears, select a firmware version and click OK. If you select Other, you will be prompted to manually locate the firmware update.