Resolve issues between iTunes and third-party security software
Test your connectivity
Check your hosts file to make sure that it's not blocking iTunes from communicating with Apple's servers.
If you’re having issues using AirPlay, Home Sharing, iTunes, or Remote, test the connectivity between the computers or devices in your house. They should be connected to the same network and subnet in order to function properly.
If you're still having trouble, continue to the next section.