Dealing with Apple iOS updates ultimately prompted my search for old firmware. Here’s how to grab the precise version desired for your iPhone / iPad.
After Steve left the building, Apple gifted its version of Maps. That debacle alerted all to the morphing of “just works” → → “just irks.”
Wiz kids later presented indisputable proof of Apple’s intentional slow-down of older devices, typically around the time newer devices dawned. End result: I stopped buying Apple hardware. The aging iMac and MacBook Air gave way to a ChromeBook. The iPhone 6+ remains, as does the first generation iPad Pro. When either dies, I’ll figure out the replacements.
Meanwhile, iOS updates continue their Windows Vista mimicry, inspiring anything but confidence in Apple’s quality control. As a direct result, I googled where and how to get my hands on older firmware:

Where To Download iPhone Firmware Files