Apple Mail and Accounts cannot verify account name or password for MS Exchange high sierra 2021

I have three computers... the only computer that will allow Exchange to function properly is the one with OS Big Sur installed. The other two cannot be upgraded higher than OS High Sierra.

Each has an older Exchange email account. But only the big sur computer will allow my new Exchange email account.

Deleting the account and re entering it many times and many ways has failed.

Changing the password on the Exchange account many times has failed.

Removing old passwords from the Keychain has failed.

Login from the website works. So the password is not defective.

Calling Godaddy has failed.

What is the problem? Why can't I load a new email account? Why isn't Apple Mail or Accounts able to verify my account name or password?