iphone4 can't connect to iCloud

This question was already here. "I wanted to use my old iPhone 4 (iOS 7.2) and it just won't let me connect to my iCloud. I keep receiving txt on my other iOs devices that my iCloud account wants to be accessed by another device, and even get a security code, but old iPhone 4 doesn't let me put in this security code."

However on my iPhone 4 when I try to go to iCloud.com there is an error "connection Error-iCloud encountered an error while trying to connect to the server". So I don't have access on my iCloud account on my iPhone to switch to two step verification which should supported in iOS 7.

Any suggestions ? Thank you in advance for your help.