The Update Server Cannot be Contacted when Updating iTunes

Hello guys. I am checking for an update in iTunes, and when I clicked on it, an error appears stating that
The iPhone software update server could not be contacted.
My internet connection is active as I can connect with iTunes store. The error is also stating to try again, but I am trying for almost a day and yet the error is still re-appearing.
How can I fix it?

Error message:
The iPhone software update server could not be contacted.
Make sure your network settings are correct and your network connection is active, or try again later.
