So I ran through the test on Microsoft's Remote Connectivity and fail.
The Microsoft Connectivity Analyzer failed to obtain an Autodiscover XML response.
None of the expected XML elements were found in the XML response.
HTTP Response Headers:
Content-Type: application/xml; charset=utf-8
Date: Wed, 17 Oct 2018 19:49:26 GMT
Elapsed Time: 1207 ms.
Any gurus on AutoDiscover know what the problem is? P.S. it's not working on Outlook 2016 and we're using SRV records.