Rollback iPad 4 with ios 10.3.4 to ios 8.4.1
It is necessary to do after the system rollback!
After the system rollback iOS to version 8.4.1, you need to reset to factory settings, otherwise applications from the App Store will not download applications!
Link how to pass two-level authentication on iOS 8.4.1
• Двухфакторная аутентификация на ios 8.4.1
A method that will help to return to your iPad 4 iOS 8.4.1 I suggest to study this simple method. Whether it will be the best choice for you is up to you to decide. Since all the same programs already require minimum versions of iOS for installation from version 9. And version 8.4.1 may not be so relevant. But it is quite possible that the system performance will be a little higher than the system iOS10.3.4. To install you will need Jailbreak. The process of system rollback itself if Cydia is installed takes place without the participation of a computer.
To install Jailbreak you will need 3uTools
https://www.3u.com
How to install Jailbreak
• Jailbreak для ipad 4 на ios 10.3.4