iCloud won't verify on Iphone

HI

im having some trouble with iCloud on my iPhone. I signed out of iCloud as I was having issues with some shared photo albums and now when I go to sign in, iit sticks at the verifying stage and won't move on. iCloud on my iPad is working perfectly with the same details that i am trying to use on my iPhone. Any ideas as to how I can get this back up and running on my iPhone?