To rule out the common suspect: The APN settings have been changed to the Straight Talk ones. Went from unlimited plan on AT&T to Straight Talk because AT&T is just a ripoff and they started throttling me. Started on ST around July 25th. I'm on an iPhone 4S with 5.1.1. jailbroken. The data worked for the first few week without any trouble. Then one day, all of a sudden it stops working. Sporadically it would work, but 90% it wouldn't. I would try resprings and reboots, but to no avail. Called ST customer service but they claim that their APN setting doesn't support iOS 5.1.1. which is obviously a crock because it worked on 5.1.1. for weeks before it stopped. They reset my account settings or something and then it worked for a little bit but again stopped. Tried doing a clean install of iOS6. Worked for about half an hour then stopped again. Then I did a clean install to 5.1.1. Same story. Now I just re-jailbroke it and went back to my preferred settings because I like my jailbreak tweaks. Another assumption could be that they 'threw me off' the unlimited plan but I don't tether nor do I even use up much of the data (I'm on WiFi at work and at home) so maybe 400-500 MBs in the few weeks of just browsing and streaming Rdio. No Youtube. So, I really doubt that they did that. I'm sure CS would've told me. SMS and calls work normally. It's only the data and it's a pain because I use the phone mostly for data. Here is a screenshot of the error I get when trying to browse and unsuccessfully loading a page. I have no idea how to fix this.