Two Factor Authentication knocked out email

Hello - Yesterday I set up multi-factor authentication on my email Office 365 account. I did not change any passwords, just enabled the authentication. All was working fine on computer, logging onto email via browser and across all devices.

This morning, email works on computer and when logging on via a browser but no longer works on iphone. It says that the password for the Exchange Account is wrong. I have re-entered password in box displayed but it doesn't recognise it. I have gone to settings / mail / accounts / exchange / and re-entered password there. It says it cannot verify it. The only info blank in my settings is Domain. I'm not sure if this is relevant or what to enter here.

It says my emails were last updated at midnight - so suspect there has been a glitch with one of the Apple systems recognising the change.

Help would be very much appreciated. Thank you