I just got Autodiscover working by running this command below: set-OutlookProvider -id EXPR -CertPrincipalName mydomain.com set-OutlookProvider -idWEB -CertPrincipalName mydomain.com However, I had to renew my SAN certificate (renewed with all the same names, i.e. domain.com, mail.domain.com, etc,) and after I renewed my SAN certificate it changed the "issue to" on the certificate from mydomain.com to mail.mydomain.com I figured I'd just run this command to resolve the issue: set-OutlookProvider -id EXPR -CertPrincipalName mail.mydomain.com set-OutlookProvider -idWEB -CertPrincipalName mail.mydomain.com Didn't resolve the Autodiscovery issue, and I'm not sure where else to look to resolve the issue. When I attempted to autodiscover from the internet, I get stuck in a loop where it just keeps asking for username and password. Any help would be greatly appreciated!

Hi, Regarding this issue, please make sure the manner of the authentication is identical on the external client and Exchange server. The detailed steps are as below: On client side, Exchange Proxy Settings in the Connection tab of the Account Settings. On server side, Outlook Anywhere in EMC and RPC Virtual Directory in IIS. After that, please check whether you have configured the msstd url in Connection settings under Exchange Proxy Settings button, please keep the url is the same with the CertPrincipalName of the EXPR provider. Thanks Allen