We are running the Microsoft Office 365 Support Assistant before setting up the Azure AD Connect tool for directory sync, but the domain verification (step 2) reports that our .com is non-routable and this type of domain is not supported.
The domain is already verified in Office 365 and has no problems. Our internal domain is the same as our external domain (domain.com) and we only have a single UPN (domain.com). We are using our own DNS and have not added the Office 365 DNS entries (reported DNS errors are ignored in the portal). We are not using a sub-domain.
Does anyone know why the domain verification step is reporting that our .com is non-routable?