Deleted now cannot re add yahoo mail
I suddenly stopped receiving yahoo mail in Ipad and iPhone mailbox. After reading suggestions I deleted the yahoo account. I then tried to re add the account at least ten times and it will not add. I sign in to yahoo, it appears to be adding and then goes right back to page that says add accounts. i have tried to rea add yahoo mail at least 12 times. I have restarted several times on both iPhone and iPad. Help!
iPad Air Wi-Fi, iOS 11.2.5