When our community went live for AT&T U-Verse, we jumped right on the opportunity to get a service with advanced voice, data and TV on the same line. Unfortunately, we found out that U-Verse requires you use to use their router. So we had to replace our beloved Airport Extreme, right? Not quite.
Our situation was U-Verse related, but others may have situations whereby your Extreme can no longer provide Internet routing functions. Fear not, because you can still take advantage of its features with Bridge Mode. Bridge mode essentially turns off the Internet routing portion of the Airport, but leaves intact all of its other features such as Wi-Fi, printer sharing, disk sharing, and Time Machine support.
First, unplug all network cables from the Airport and reset it so you are starting with a clean slate. Instructions to reset can be found here.
Next, plug an Ethernet cable from your computer into one of the Ethernet ports on your Airport Extreme. You can configure via Wi-Fi, but wired is easier. If you do it over Wi-Fi, you’ll need to search for your particular Airport.
Once you are connected to the Airport base station (either via ethernet or Wi-Fi), launch the Airport Utility on your Mac. The utility is located in /Applications/Utilities. Once it loads, you will see your Airport router listed in the upper left corner. If the router doesn’t show up, make sure you are physically connected to its network from your Mac.
Click “Manual Setup” towards the bottom of the window and then click the “Internet” icon that appears at the top of the window.
After you click the “Internet” icon, the Internet Connection tab should appear. At the bottom of this window, you will see an option for “Connection Sharing.” By default, this is probably set to “Distribute a range of IP addresses” or “Share a public IP address.” You want to change this so that it says “Off (Bridge Mode)”
At this point, you are done. The Airport is setup for Bridge Mode, but you’ll want to configure a few more things.
Configuring Your Bridge
To configure the Wireless Security and Wireless Network Name, click the Airport icon at the top of the window and then click Wireless.
If you reset the Airport first, you’ll want to click the Base Station tab to rename the Base Station and create an Airport Extreme Password (which may or may not be the same as your wireless password).
If you want to share a connected printer or disk, click the Printers and/or Disks tab as applicable. Personally, I use the USB port and Disks function to have a remote Time Machine shared by multiple computers.
Once you have made all the changes you wish to make, click on “Update” in the lower right corner, and your Airport base station will restart. At this point, you can disconnect from the ethernet port and now must plug in the ethernet cable from your ISP-provided router into the Broadband port of your Airport Extreme.
After it restarts, the Airport Extreme indicator in the front should go green. You can test the bridge by connecting to your Airport via Wi-Fi (or ethernet if you want) and surf the Internet as well as see any disks or printers you might be sharing.
Keep in mind that there are a few limitations of bridge mode. Because the Internet routing features of the Airport are not used in Bridge Mode, certain features that rely on special functionality of the Airport router, like Back To My Mac, may not work. Additionally, port forwarding (for things like games or Bit Torrent) needs to be done using your ISP’s router’s web interface, rather then the Airport Utility. Some ISP routers have a special mode called “DMZ” which allows you to use these features on the Airport, but setting this up is router-specific and often subject to change.