Purchased my Airport Extreme about a year or two ago. Model A1408. It worked great for awhile and then something happened, to be honest, I have no idea what happened. One day I was no longer able to get online through my router. I am currently using Comcast modem. For weeks I tried calling Comcast to help me but they can only help so much. All I want to do is connect online using my router. I spent about 100.00+ for this router and I want to get good use out of it! I have two problems, when trying to connect to my "network name" it tells me that I do not have a DNS address and the connection is "disconnected" (when clicking on the globe in Airport Utility). However, the network name is showing up and the green light is there. So, I know without a doubt the internet is on. This is all foreign to me. Why do I need a DNS address, now? What happened to the one I was using previously? Did Yosemite OS X or Comcast removed something? Please help me.