Q: The screen shows "Cannot get Mail" The connection to the server has failed. What is the cause of this and why is spite of that notification the mail is received?

The i-cloud mail comes up with "Cannot get mail"

The connection to serverhas failed.

Even with this on the screen mail is delivered but not consistantly.

What have I done wrong in the set-up or is there a glich in the systm?

There is Wifi conection because facebook work as does sending mail.