iPhone iOS Firmware iPhone ipsw firmware download that provided by Apple, when you do the relevant operation at your own risk.

IPHONE 6S PLUS 11.3.1

IPHONE_5.5_11.3.1_15E302_RESTORE.IPSW
Categories:
11.3.1
Version:
2.72 GB
Size:
April 25, 2018
Date:
Unsigned
Status:
The file can help you a lot ?