4g on atrix hd won't work after update, please help!

I just installed JB on my unlocked Atrix HD. Everything was going perfect until I realized that my 4g network isn't working. I can't get on the internet at all. It gives me this "server error" message, no matter what I do. I went to the point where I even did a factory reset. No help. I can text and the wifi works, but I can't get on the internet or do anything related to the internet without using the wifi. Anyone know how to fix this/is having the same problem?

I've been trying to find a solution everywhere, since I REALLY REALLY need my internet connection once I leave my house.

This is usually an "APN" issue. You'll have to go into your wireless settings and make sure there's proper data APNs set (google "AT&T data APN"). if you're having trouble on your own, you can always call or go into an AT&T store and have them re-configure it...