It's unfortunate that your service provider says that they cannot help, but when they do go ahead and tell you how to hook things up, the instructions are wrong.
You will need to start all over again as follows:
- Disconnect the Ethernet cable that is coming from the modem
- Push the reset button on the modem (if presenet) and then power it down by pulling the power plug either from the back of the device or from the AC socket in the wall.
- Leave it off for at least 20 minutes, longer will not hurt.
Perform a Factory Default Reset on the AirPort Express as follows:
- Power down the Express by unplugging it from power
- Wait a moment or two
- Hold in the reset button (next to the audio port) and continue to keep holding it in for another 8-10 seconds while you plug the Express back in to power
- Release the reset button after the hold period and allow 40-45 seconds for the Express to restart to a slow, blinking amber light
- Now power down the AirPort Express
When 20-30 minutes have passed after you poweed down the modem....
Connect the Ethernet cable from the modem to the AirPort Express
Power up the modem and let it run by itself for 4-5 minutes
Power up the AirPort Express exactly the same way
On your Mac....
- Open Macintosh HD > Applications > Utilities > AirPort Utility
- Click Continue to follow the guided setup as summarized below
- Page 1.....Name the AirPort Express and establish a device password (write that down)
- Page 2.....Create a new wireless network
- Page 3.....Enter the name that you want for your wireless network and establish a wireless network password (write that down)
- Page 4.....Share a public IP address
- Page 5.....Configure IPv4 using DHCP. No other information is needed on this page
- Page 6.....Summary of settings and Update to save settings
Allow 40-45 seconds for the AirPort Express to restart and display a green light
Using your Mac, locate the name of the wireless network that you setup and enter the password to connect
Thanks so much; that's exactly what was needed. I was doing this setup for my daughter in her new apartment and had never worked with Comcast before. After this experience, I don't think I'll ever work with them again.
We're up and running now. All I have left to do is get her printer onto the network, which I haven't tried to do yet. Hopefully, it will go smoothly now that the network is up and running.
I appreciate your help.