Fixing error 3194
Download TinyUmbrella. (download links on the sidebar of their site)
Backup links: (these may be outdated)
TinyUmbrella for Windows 5.10.14
TinyUmbrella for OS X 5.10.14
Open TinyUmbrella (It requires admin account on the computer)
Select your iPhone and then click on the “Advanced” tab.
Untick the box “Set Hosts to Cydia on Exit (If you need a clean restore from Apple uncheck this box)” as seen on the screenshot below
Apply the changes.
If the phone is jail broken then follow this
Close the iTunes.
Locate the hots file:
in Mac OS X, it is /etc/hosts
in Windows, it is c:\windows\system32\drivers\etc\hosts
Open the hosts file with Notepad.
With Administrator privileges, at the bottom of the Notepad, type the following line:
Connect iPhone to computer.
Run the iTunes.
Turn off iPhone/iPad/iPod and hold down the sleep and power button for 10 seconds.
Release the power button but hold onto the home button until the iTunes displays the device is in recover mode.
Use iTunes Restore feature with the iOS device as usual.
After iOS have been updated, delete the "18.104.22.168 gs.apple.com" line from the hosts file, and then the iTunes can correctly update again.