Download iOS 9.3.6 (13G37) for iPhone 4[S]

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

✅ This IPSW firmware is Signed

Firmware Identifier iPhone4,1
iOS Version 9.3.6
Release Date 2019-07-22
Update Date 2019-07-01
Sha1sum
6ccddbfdf4a0d6747924252d379ad6d52f7d4ea8
Sha256sum
2466a99001c9e091e22f330a1c97a231179d1679f58fd9d1cf0c1694ca8261bd
md5sum
26f4c6077e5f9beda57f100cda21e464
Size 1.50 GB
FileName
iPhone4,1_9.3.6_13G37_Restore.ipsw
Status

Download IPSW (1.50GB) Check device info
Release Notes

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

iOS 9.3.6 addresses an issue that could impact GPS location performance and could cause system date and time to be incorrect. This update is recommended for all users.

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

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