AT&T U-verse modems all come pre-installed with default names (2WIRE123) and default passwords (10 digits). That is boring, and not easy to remember. Picking your router from all your sheep neighbors can be difficult if your urban density is high, and the 10 digits are not the ones you need.
If you connect your computer to the modem directly with an ethernet cable, you can manipulate these things. There is a default IP address for ALL routers. If they’ve politely implemented it, you can access it at http://192.168.1.254/ – though there are other addresses used by different manufacturers. The U-verse modems have a quite nice interface to manipulate the settings. (I’ve recently found that http://gateway.2wire.net/ might get caught by the modem as well.)