Iphone Firmware Flash Tool Link | High Speed

Apple "signs" firmware versions. You generally cannot flash an older version of iOS once Apple has stopped signing it (usually a few weeks after a new update).

The iPhone Firmware Flash Tool, commonly referred to as the iPhone Flash Tool, is a software utility used to flash or restore iPhone firmware. This tool is particularly useful for iPhone users who need to restore their device to its factory settings, update to a newer version of iOS, or recover from a software-related issue. iphone firmware flash tool link

Download 3uTools via 3u Official Site