For everyone out there looking to switch to AT&T U-verse, I thought I would supply this handy tip. The first thing you will realize when you get the service installed is that the modem they supply has a built-in router. The router AT&T supplies is only 802.11 N 2.4 GHz. If you plan on streaming HD videos from a local file server or transferring large files via Wi-Fi then you will want to use your own router with the latest and fastest 802.11 ac Wi-Fi. Here is how to set up your own router to work with AT&T U-verse.
Assuming the AT&T representative set up your internet service and you can access the web, the first thing you will need to do is plug in your own router. You will need to run an Ethernet cable from the WAN port of your router to the LAN port on the AT&T router. Next head over to your computer and type 192.168.1.254 into your web browser. This is the IP address of the AT&T modem and will allow you to configure the settings. You should end up on a page that looks like the one shown below.
You will then want to click on the wireless setting under Key Things to Do using your gateway. Once on the wireless setting you will need to find the Wi-Fi setting and switch it to disabled.
Now you are done with the AT&T modem and can move onto configuring your own router. For my demonstration I will be using an AirPort Base Station like the one shown below, but the process is similar for most routers.
Enter the IP address of your router into your web browser or in my case open the AirPort Utility application. After launching AirPort Utility or entering your IP address you should come to your router settings.
Under the network section of your router settings you should find an option for DHCP or Bridge mode. You will need to put your router in Bridge mode since you are connecting a router to a router. This will allow your router to use the IP address of the AT&T modem and essentially only broadcast Wi-Fi.
Assuming you did everything correctly you should be able to see your Wi-Fi network and be able to access the Internet.