IPhone Software Update Error – iTunes

Hello everyone,
The time I click on the “Check for Update” button in iTunes, I face an error message which directs me to connect with the Internet via an Ethernet Cable. Though I feel no issues connecting to the iTunes store in iTunes so there is no doubt I have got issues with the internet access but still it says try again later though I tried again and again for ages but nothing happened well.
I’m puzzle whether the Apple or iTunes has fault with?
