On-prem AD: shortname.local, Windows 2012 & 2019 DC
On-prem Exchange: fullname.com
fullname.com is verified on Azure AD
Trying to install AzureADSync on Win2019 DC. Added fullname.com as UPN suffix in AD Domains and Trusts, and change UPN suffix for all users to @fullname.com. Now, I'm stuck at "Connect your directories" phase of the ADConnect install. After adding shortname.local, at the Azure AD Sign-in screen, it shows
shortname.local Not Added
Longname.com Verified see screnshot
And the warning that user will not be able to sign-in to Azure AD w/ on-prem credentials, which is the ultimate goal as well as setting everything correctly for future migration of on-prem Exchange and Office to cloud.
Is changing the on-prem domain name to fullname.com the only solution or is there another easier option? Please advise, thanks in advance.