This is an iTunes error that has to do with local settings. A few things you can try:
- Verify the computer's date and time are accurate.
- Check that your security or firewall software is not interfering with ports 80 or 443, or with the server gs.apple.com.
- Often, uninstalling third-party security software will resolve these errors.
- An entry in your hosts file may be redirecting requests to gs.apple.com.
- Internet proxy settings can cause this issue. If you are using a proxy, try without using one. Test restoring while connected to a known-good network.