OP doesn't sound like he has a modem you noobs. He has the AT&T Fiber Optic connection.

OP:

You will need to go in your web browser and log into your router to properly setup the connection. Take the ethernet from the wall and plug it into the internet port on your router. Then plug the desktop into one of the open switch ports.

1. In the address bar of Internet Explorer type 192.168.1.1
2. Leave the user name field blank and enter admin for the password when it prompts
3. You will see at the top of page "Internet Connection Setup" and it will probably be on "Automatic DHCP" You need to change this to PPPoE. It will show a user name and password field once you change it to PPPoE. Enter your primary AT&T email address and password here.

Save the settings and you should be online from there. PM me if you have problems. Don't listen to these noobs in here, obviously they aren't aware of the different type of DSL connections out there.