Apple is no longer signing iOS 10.3.3 and iOS 11, which means those who haven't rolled back before completely missed their chance. All that remains is to wait for iOS 11 fixes
Yes, as sad as it may sound, you can no longer downgrade from iOS 11 to iOS 10.3.3.
And Apple specifically removes the ability to rollback and actually use older versions. This is done to prevent the zoo of different versions known for example by Android.
Now you can upgrade to iOS 11.0.2, but rollback is only possible to iOS 11.0.1. Only 2 of these systems are signed by Apple.
Let's also remind that iOS 11.1. is already in beta. In addition to fixing many bugs and new emojis, this version is notable for fixing the low autonomy of iOS 11.
If you are anxious to fix performance issues or enjoy getting all the updates first, you can get iOS 11.1 beta 1 by signing up for Apple's beta testing program
The Topic of Article: Can't roll back from iOS 10.3.3 and iOS 11 anymore.