cannot run iOS 6 as they were released with much newer software .

If WiFi is grayed out after downgrade, you have a baseband mismatch. Simply re-run the downgrade tool, but this time check the option "Restore with Baseband."

Select whether you want to boot to iOS 6 or iOS 9 by default.

Sometimes the most interesting piece is the one that admits: some doors are sealed for good.

No activation issues, easy to switch back. Cons: Takes up significant storage space. What to Expect After the Downgrade