Trouble connecting on ipad and iPhone

Trouble connecting on ipad and iPhone

Has anyone noticed this issue? From time to time I get a message telling me that my username or password are wrong and ipad can't connect to my email. An hour later it could be fixed on its own. That's not the strange part. I also notice if I go to the web and check my mail when it says this, I notice I have no mail. When it works again is when I get an email. Could that have something to do with why I get this message?