Have you been trying to downgrade your iOS 5.1.1 running device to iOS 5.1 or iOS 5.0.1 using RedSn0w when you stopped by a rather disappointing message saying “Restore failed”? The iPhone Dev team has found the solution to your problem.

Let’s take a look at the bug fixes the latest version of Redn0sw brought. RedSn0w 0.9.11b4 does not interfere with nearby devices with the option of Wi-Fi syncing enabled. Moreover, this tool offers tethered jailbreak support for A4 devices and earlier that are running on the latest operating system released by Apple with proper “Stitching” and “Custom”.

We’d like to inform all iPhone and iPhone 3GS users who find maintaining their baseband a necessity, that RedSn0w 0.9.11b4 can produce the NO_BB_* custom IPSWs for 5.1.1. A NO_BB_* version of 5.1.1 IPSW can also be created using RedSn0w’s “Custom IPSW” button which enables you to bring back to that IPSW as an alternative to the stock one. Restoring your iPhone to a stock Apple IPSW is probably not a very wise idea as you will end up locking your iPhone.

Do not forget! This is still a tethered jailbreak except that old-bootrom 3GS users.

Download redsn0w 0.9.11b4:

• Redsn0w 0.9.11b4 for OS X
• Redsn0w 0.9.11b4 for Windows (be sure to run in Administrator mode)

Stay tuned as we will be posting soon a piece with a detailed guide on how to create custom iOS 5.1.1 IPSW (NO_BB_* version) and how to restore the custom firmware on your iPhone 4 or iPhone 3GS devices without having to upgrade the basebands.