. Since standard IPA files for the modern YouTube app are incompatible with such old firmware, you must use legacy versions combined with specific "fixes" to restore connectivity. Method 1: Installing the Official Legacy YouTube IPA
For iOS 5.1.1, two versions are commonly used. You can find verified legacy IPA files on the Internet Archive . youtube ipa for ios 511 verified
Title: The Last Compatible App
Ensure your IPA is version 5.x . Versions 6 through 12 will likely not function on iOS 5.1.1. Use Sideloadly and iTunes 12.6.5.3 for the highest success rate on Windows. youtube ipa for ios 511 verified