Apple AirPort Time Capsule 802.11n (4th Generation) - Manual (Page 29)

29 Chapter 3 TipsandTroubleshooting
IfYourTimeCapsuleStatusLightFlashesAmber
The Ethernet cable may not be connected properly, your Time Capsule may be out
of range of an AirPort network, or there may be a problem with your Internet service
provider. If you’re connected to the Internet with a DSL or cable modem, the modem
may have lost its connection to the network or the Internet. Even if the modem seems
to be working properly, try disconnecting it from its power supply, waiting a few
seconds, and then reconnecting it. Make sure your Time Capsule is connected directly
to the modem via Ethernet before reconnecting power to the modem.
For more information about why the light is flashing, open AirPort Utility, select your
Time Capsule, and then choose Manual Setup from the Base Station menu. Click Base
Station Status to display information about the flashing light.
You can also select “Monitor base station for problems” in AirPort preferences.
If the base station has a problem, AirPort Utility opens and walks you through
solving the problem.