I know this is an old topic, but I've been having this issue with my AT&T Samsung Galaxy Note 2 as well for the fourth week in a row now. My phone will say I have 3/4 bars of 4G LTE, yet I can't connect to the Internet, not even to retrieve my email. I've chatted with more than three AT&T service reps now, and my issue was even escalated last week, and now I'm just waiting for my replacement device. I even got my sim card replaced on the second week of this ongoing issue, and that did not seem to resolve it at all. I'm hoping that I won't have the same problem when I get the new phone either today or tomorrow. If not, I might just have to cancel my plan because I don't think it's right to have to put up with this for almost a month now. I even did a factory reset on my phone, and the issue still persists.