Download iOS 13.3.1 (17D50) for iPhone 6s+

You will have to note that you can only restore signed IPSW firmware files using iTunes or 3utools.

❌ This IPSW firmware is not being Signed by Apple

Firmware Identifier iPhone8,2
iOS Version 13.3.1
Release Date 2020-01-28
Update Date 2020-01-22
Sha1sum
56ac1fb10f896629d605e628341e654388ce49e2
Sha256sum
3577c1be4d4f3b13e8a503103d982855a8f335ac63ab0ff1a40aea6ec9531c1b
md5sum
dce58c37f1356a489e63c0c35e4061e5
Size 3.63 GB
FileName
iPhone_5.5_13.3.1_17D50_Restore.ipsw
Status

Download IPSW (3.63GB) Check device info
Release Notes

It should be noted that these are the official release notes for the from Apple

iOS 13.3.1 includes bug fixes and improvements. This update:

For information on the security content of Apple software updates, please visit this website:

https://support.apple.com/kb/HT201222