The iPhone 4s, iPad 2, and iPad 3 were notoriously difficult to jailbreak on iOS 9 due to KPP (Kernel Patch Protection). Phoenix is a semi-untethered jailbreak that runs on these 32-bit devices. Without the legacy page, installing Phoenix usually requires a computer (Cydia Impactor), but legacy.html allows for direct installation.
Older iOS versions often struggle with modern HTTPS certificates. Installing the InvoxiPlayGames certificate via Cydia allows Safari to load modern websites again. jailbreaks.app legacy.html