I've got an iPhone 4 running iOS 5.0.1. I tried updating to 5.1.1 but it said my iPhone was eligible for such update. I tried editing my hosts file and running TinyUmbrella but didn't solve the problem. I now get iTunes error 11, and when I put the iPhone in pwned DFU and use my custom made IPSW I get error 1600. I tried restoring back to 5.0.1 but still the same problem... Please help!