I would recommend that you do the following as a minimum:
- Power-down the modem, AirPort base station, and computer(s).
- Disconnect the AirPort base station from the Internet broadband modem.
- While all of the devices are powered-down, perform a "factory default" reset on the base station. This will get it back to its "out-of-the-box" configuration and make setting it up much easier, especially if you use the "Assist me" process within the AirPort Utility. (ref: Resetting an AirPort Base Station or Time Capsule)
- After the base station resets, go ahead and power it back down.
- Reconnect the AirPort base station to the Internet broadband modem.
- Power-up the modem; wait at least 10-15 minutes to allow it adequate time to initialize.
- Power-up the AirPort base station; wait at least 5-10 minutes. Note: The AirPort's status light may continue to flash amber after it has intialized. That is because, there may be some additional configuration items necessary, like setting up wireless security, before the overall setup is completed to get a green status.
- Power-up your computer(s).
In this basic configuration, the AirPort base station will broadcast an unsecured wireless network with a Network Name (SSID) of Apple Network NNNNNN. Network clients, connected to the base station either by wire or wireless, should now be able to access the Internet through the ISP's modem. Once Internet connectivity has been verified, you can use the AirPort Utility to configure the base station for wireless security and any other desired options. Please post back your results.
First of all, thank you for posting. It was a great help. That said, things didn't go as smoothly as I would have liked. I think the biggest help was performing the factory default reset. Going through your steps only got me so far though. It seemed that after performing the reset, I then had to connect my computer back to my modem via the ethernet cable in order to see the default (unprotected) network listed as Apple... I tried skipping this step at first, as per your instructions and I was led to the same issues - my Airport Utility would not recognize the Airport Express.
In any case, once I did this, I then unplugged the ethernet from the computer, reset the cable modem and plugged it back into my Airport Express. I then plugged it in and Airport Utility kicked in and I was able to set up a password protected network.
I'm really surprised as to how difficult this was. Sure, with a bit of research and asking around it was achievable, but I would really like to see more troubleshooting intervention triggered by the Airport Utility to guide the user in trouble when problems like this arise.
Thanks so much for your help. I was going a bit crazy trying to figure this out.