Using a (iOS App Store Package) for devices running iOS 5.1.1 —such as the first-generation iPad—is a common way to breathe life into legacy hardware. While modern versions of Netflix require much newer software, certain "last compatible" versions still exist that can sometimes be sideloaded or downloaded through specific workarounds. The Best Netflix IPA Version for iOS 5.1.1
If the app refuses to log in due to outdated security protocols, you can try the web browser: netflix ipa ios 511 best
If you are determined to repurpose an old device, these are the common community-suggested workarounds: Using a (iOS App Store Package) for devices running iOS 5
Even with the "best" IPA, you will encounter issues. Here is the troubleshooting guide: netflix ipa ios 511 best