As if the circumstances surrounding the current jailbreak situation weren’t dire enough already, Apple has stopped signing both 11.1.1, iOS 11.1.2, and tvOS 11.1.
The latest move by the Cupertino-headquartered company makes it impossible to downgrade to firmware versions vulnerable to Ian Beer’s recently-publicized tfp0 exploit until downgrading tools receive support for iOS 11. That said, hopefully everyone had adequate time to prepare their devices beforehand.