Manual Fetch works during day but Fetch goes full auto at night
I want my iPhone 11 running OS 14.5, to fetch mail only manually. During the day, that's how it works, perfectly. But at night, during the iPhone's Do Not Disturb time, it appears that the iPhone turns itself on every hour or two and reaches out for mail. I'd really like to stop the behavior, but how?
iPhone 11 Pro, iOS 14