With such a large number of connection issues with Outlook 2016 connecting to Office 365 you would think someone would have the definitive answer to these persistent issues. It is unfortunate that the issues that plague Outlook 2016 are not all related. Hopefully after you have read this technical note you too will be able to resolve your issue. Although this is not the fix that will fix all Outlook connectivity issues, but then again it might fix yours.
I guess starting with the obvious is always a good place to begin.