Hi all! I own an iPhone 6 with iOS 9.3.3. I didn't update my iPhone because I was afraid that it will go slow. But now, I reached the situation when I can no longer download new apps because the App Store is requesting at least iOS 10. (when I'm downloading a new app, I download it first on the iPhone of one of my family member, then the App Store on my iPhone allows me to download an older version of the app). Long ago, my iPhone downloaded iOS 10.2.1 in the Settings menu. I tried to push the "install" button but my iPhone says "unable to verify update". I guess that is because Apple is no longer signing it? My questions are the following: - is there any way to update to iOS 10.2.1 from 9.3.3 ? - if no, should I update the iPhone 6 to 12.1.2 or should I keep it under 9.3.3 because the newest firmware will turn it very slow? Thank you!