Microsoft Enterprise Exchange Problems on iOS 16

Since the update to iOS16 and the change to modern authentication, I cannot get my business Exchange account to work properly on the native iOS Mail app for any iPhone or iPad device.

This problem has persisted since iOS16.0 through 16.0.3 and even the forthcoming iOS 16.1 RC. Push mail, or Fetch mail, no longer works. And when in the Mail app for the iOS device, it either gets stuck on "Checking for Mail" or it eventually fails with an error saying “Cannot Get Mail: The connection to the server failed”. It randomly will start fetching mail again, though not through Push or Fetch, only to get stuck at random intervals with "Cannot Get Mail: The connection to the server failed."

I've tried deleting and re-adding the account, resetting all settings on the devices, and even reinstalling iOS 16 fresh and re-adding the accounts. All to no avail. We've checked the Azure AD for error messages during these failures, and we cannot find any errors.

Absent an iOS 16 bug that may or may not be addressed, is there anything I am missing to fix this? I do not want to use the Outlook app, because I manage multiple accounts through the Mail app and do not want to be using multiple apps just to manage mail.