Airport Extreme flashing amber light

A persistent, blinking, amber status light indicates that your Wi-Fi base station may require your attention.

How to resolve a blinking amber status light alert

Launch AirPort Utility to determine why your Wi-Fi base station status light is blinking amber. 
Apple recommends that you use AirPort Utility 5.5.2 for Mac, AirPort Utility 5.5.2 for Windows, or a newer version of AirPort Utility if one is available.

1. AirPort Utility 5.2 or later opens automatically if your Wi-Fi base station requires your attention. You may also choose to launch AirPort Utility at any time.
 Do not use any version of AirPort Utility earlier than 5.0.
   In Mac OS X, AirPort Utility is located in the Applications > Utilities folder.
   In Microsoft Windows, AirPort Utility can be located by clicking Start > All Programs > AirPort.
   Note: You may also locate and download the latest Wi-Fi base station firmware and software by clicking here.
2. In the AirPort Utility window, locate your Wi-Fi base station and double-click on it to open the Summary window. Note: If you have more than one Wi-Fi base station, double-click on the icon for the Wi-Fi base station that has the amber circle next to it.
3. When the Summary window appears, double-click the amber circle to the right of Wi-Fi base station Status to open the Status window.
4. The Status window lists any conditions that require your attention. Respond to each item until there are no more items listed.
   Important: You must reset the Wi-Fi base station using the reset switch to re-enable checking for the conditions you ignored.
5. Eliminating the blinking, amber status light may require making changes to a specific setting, or putting a checkmark in the "Ignore" checkbox beside any option you don't wish to change. A checkmark simply tells the AirPort that you are aware of the issue and you have chosen to ignore it. For example, you may wish to leave your AirPort open without a password so that anyone can join your wireless network.
6. Click Update to apply your changes (the Wi-Fi base station will restart).
7. After the Wi-Fi base station has restarted, the status light should be green and not blinking. If the status light stays amber in color and blinks after the Wi-Fi base station restarts, you may repeat the steps above.

AirPort base stations: About AirPort base station status lights (LED)

The AirPort Extreme (802.11n) and Time Capsule support USB storage devices that are formatted as Mac OS Extended (HFS-plus), FAT16, or FAT32. Formatting a storage device as Mac OS Extended with journaling is recommended, as it may provide some more resilience if the device is removed or powered down while in use.

Note: ExFAT and NTFS formats aren't supported.

AirPort Extreme (802.11n) and Time Capsule: USB storage device ...

Change your Airport base station from using DHCP and NAT to bridge mode?

You can change the AirPort Base Station to operate in Bridge Mode as follows in AirPort Utility:

Click on the AirPort Extreme icon, then click Edit in the small window that appears

Click the Network tab at the top of the window

Make sure that the setting for Router Mode = Off (Bridge Mode)

Click Update to save the new settings

Allow a full minute for the AirPort Extreme to restart

Then, very important......power off both your modem and the AirPort Extreme

Wait a minute or two

Start the modem first, and let it run for a full minute

Start the AirPort Extreme next and let it run for a minute

You should be all set with a green light on the AirPort Extreme