The huge amount of traffic on Apple servers means that it will sometimes fail to keep up with some of the requests.Therefore, it is best to wait for a few hours or days before trying again, as the load on their servers will be reduced.Close the Terminal and move on to the next section of this article, "Address TCP/IP filtering, firewall, or security software." 7. If necessary, find a different network connection to restore the device.Add the # symbol and a space ("# ") to the beginning of the gs.entry. For example, if you're restoring at work, try to restore at home or on a friend's computer and network.Resetting the hosts file affects software services that rely on hosts file redirects. Enter the password you use to sign in to your computer and press Return. If you don't see a window similar to the one below, make sure you're using a nonblank administrator password. Navigate using the arrow keys and look for an entry containing “gs.apple.com”. If your computer uses a managed network, refer to your network administrator.If you're using Windows on a business computer, consult your IT department to be sure applications work correctly after you reset your hosts file. You won't see text appear in the Terminal window when you type your password. If you don't see any entry containing gs.apple.com, then the hosts file isn't related to the issue. Proxies, firewalls, and other network security measures can cause these errors.If your excitement of installing the i OS 11.3 update which was just released was cut short by “Software Update Failed: An error occurred downloading i OS 11.3” error then I can understand the frustration.But thankfully there are some solutions you could try.
An unknown error occurred (36)” What operations cause the “Recovery Mode” while upgrading to i OS 10, i OS 9, i OS 8, i OS 7 or i OS 6?
if your device cannot be restored, that does not mean all your data are lost.
Your data will not be lost, they are in somewhere in your device.
Three are no other solutions but to manage to recover i Phone 7, i Phone 7 plus, i Phone 6S, i Phone 6, i Phone 6 plus, i Phone 5S, i Phone 5C, i Phone 5, i Phone 4S, i Phone 4, i Phone 3GS, i Pad Pro, i Pad mini, i Pad air, i Pad 4, i Pad 3, i Pad 2, i Pod touch 5, i Pod touch 4 with i Tunes.
If you successfully recover device, all your data including photos, documents, videos will be restored.