A connection issue with the Internet? Seems unlikely if the file is fully and succesfully downloaded.
Maybe a connection issue with the phone?
Kees
I am going to destroy my mac. I have tried downloading the iPhone update 4 times, each time it downloads the completes the total amount of the file but then fails saying there is a connection issue. I have extremely fast internet. My connection is fine. I updated iTunes. *** do i need to do?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic