Since Android 5.1.1 (Lollipop) is a very old version of the operating system (released in 2015), the "download" process depends entirely on whether you are looking for an official over-the-air (OTA) update or a manual firmware file. 1. Official Over-the-Air (OTA) Update
Since this is a legacy version, the method depends on whether you have a Nexus/Pixel device or a third-party handset: android 5.1 1 update download
The represents the end of an era. It was the moment Google finally fixed Lollipop and turned it into a rock-solid operating system. For owners of legacy hardware, this update unlocks the full potential of your device, extending its life by years. Since Android 5