There is no untethered jailbreak for iOS 9.3.6, and there likely never will be.
EverPwnage. ... EverPwnage is an untethered jailbreak for 32-bit devices running iOS 7.0-9.3. 6. The Apple Wiki P0laris - The Apple Wiki ios 9.3 6 jailbreak untethered
. This means you must re-run a "kickstart" app on the device every time it restarts. There is no untethered jailbreak for iOS 9