My internet times out...

If it was fine up until a few days ago, I would scan with Malwarebytes Anti-Malware - Reviews and free Malwarebytes Anti-Malware downloads at Download.com

If I remember correctly when I was on AT&T, the lease or connection was good for three days. At the end of that time, it expired and had to be reconnected. This was done automatically. There is a possibility that this could be the source of your problem. If this is the case, you will need to talk with AT&T's broadband customer support.

What kind of an error message are you getting?

It sounds like a router setting problem. I am not very knowledgeable about the router settings and I would hate to try to tell you what to check or change. I suggest you call AT&T support, describe your problem and let the tech talk you through what to check while you are on the line with him/her. It has been over three years since I had a similar problem and I just don't remember exactly what fixed it. It was simple though.

One thing, have you tried resetting your router and your modem? You can do this by unplugging the power to them for at least two minutes and then plugging the power back in. Alternately, you can press the reset buttons with a ballpoint pen.

I would try the modem first and see if that clears up the problem. If it doesn't try the router.