Can't get Time Capsule to access internet through 2wire router / modem with AT

Question

I have internet service provided by AT&T Uverse. AT&T provides a 2 wire combination modem / router.  My Time Capsule will connect to my internal network but will not connect to the internet.  I have a steady green indicator light on the Time Capsule.  Can anyone offer any assistance? 

Answer 1

Time Capsule & AT&T 2Wire Gateway Model: 3800HGV-B
Instructions on connecting your Time Capsule to an AT&T 2Wire Modem Model: 3800HGV-B. I do know if these instructions will work for other models. Some 2Wire models require it to be set in “Bridge-Mode” or a “Router-Behind-Router”. The 3800HGV-B model does not have the ability to be put into “Bridge-Mode”.  After hours of frustrating tech support calls, mine is finally working, so I thought I would share what worked for me. Why something like this isn’t already posted, I have no idea? Although I may not have all the terms correct, I think I can explain it in a way to help others the way I wish someone could have helped me. Something this simple, shouldn’t be so hard.
The Situation
Those with AT&T U-verse are unable to connect their Time Capsule to Network.
The Problem
Apple & AT&T’s Tech Support have failed to provide solutions.
The Solution
To configure the AT&T 2Wire with the Time Capsule the 2Wire must have its router disabled, in addition to disabling both the 2Wire and Time Capsule Firewalls. The goal is to get these two device to play well with each other. The challenge is that the 2Wire Modem is both a router and a modem. The Time Capsule is also a router, so they compete with each other, thus creating the headache many of us have experienced.
Step One: Create a wireless network.
Connect your DSL or cable modem to the Ethernet WAN port on your Time Capsule.
Open Airport Utility, select Time Capsule, and click Continue.
Follow the onscreen instructions to create your new network.
Once you have finished the above steps, make sure your screens look similar to mine. Once you have the Time Capsule set up according to the directions, you still won’t have internet connection. Be sure there is a “checkmark” next to your new newly created Network.
The Situation
This above process should have set the Time Capsule in a DHCP mode, thus making it ready to receive the signal/ IP address sent by the 2Wire.
Step Two: Allow DMZplus mode
    Open your web browser and enter the address http://192.168.1.254/  This will take you to the 2Wire settings. Select Settings, click Applications, Pinholes, and DMZ. At the bottom of the page, select Allow all applications (DMZplus mode). Click Save.
Note: Once DMZplus mode is selected and you click save, the system will issue a new IP address to the selected computer. The computer must be set to DHCP mode to receive the new IP address from the system, and you must reboot the computer. If you are changing DMZplus mode from one computer to another computer, you must reboot both computers.
The 2Wire Wireless Setting must be disabled. You don’t want the 2Wire to broadcast its wireless signal. You must shut off the “Router” abilities of 2Wire. In the U-verse 2Wire Settings, select the Firewall tab, click Applications, Pinholes and DMZ. At the bottom of the page select the radio button which Allows all applications (DMZplus mode).
You will know when you are successful at shutting the wireless down by  selecting the Airport Signal in the upper right of your screen. If you see a network called 2Wirexxx, then your 2Wire is still broadcasting its signal.
The Time Capsule is setup in the DHCP mode, but isn’t able to get the IP Address because there are 2 Firewalls to address. There is the firewall of the 2Wire and one for the Time Capsule.
Step Three: Disable the Firewall.  
    One thing all the other tech’s missed, was unchecking the “Enable default host at”. Your screen should look like the below screen shot, because this disables the other Firewall that is giving you trouble. Be sure and Update after you make your changes.
    Once the changes are complete, turn the Airport off. Shut down your computer. Unplug the 2Wire and the Time Capsule and let them sit for 5 min. Next, plug the 2Wire up first and let it begin its reboot process. Then, plug in the Time Capsule and let it start to reboot. Finally, turn on your computer and open Airport Utility.
   Finally, after a complete reboot of the system, try to connect the internet. You should now be capable of opening your system and enjoying your online experience.
I hope this helps!