IOS 1.8.3 "Cannot be downloaded at this time"

Hello there I have been having trouble with my phones wifi and I talked to someone and they suggested the software update. So, I went home plugged in my phone it is now at 64 percent and has a strong WI FI connection. I press Install now and it comes up with a message saying cannot be downloaded at this time. I have tried this multiple times before and it still doesnt work. It is an Iphone 5s Thanks!