Forum Discussion
MS Teams with Exchange On-Premises
AtanasM How is the on-premises Exchange Server published to the Internet? Is Windows Server 2016+ Application Proxy used, or another reverse proxy component?
In regard to the Exchange hybrid configuration, is AutoDiscover DNS used or does the Exchange hybrid configuration use a static TargetAutodiscoverEpr?
Hello oliwer_sundgren
I checked many times and Oauth is set up correctly.
Are you sure, that enabling Group-Writeback can solve the issue?
Thanks in advance.
AtanasM How is the on-premises Exchange Server published to the Internet? Is Windows Server 2016+ Application Proxy used, or another reverse proxy component?
In regard to the Exchange hybrid configuration, is AutoDiscover DNS used or does the Exchange hybrid configuration use a static TargetAutodiscoverEpr?
ThomasStensitzki-MVP I added the local web service URLs as SPN in Azure AD and this solved the issue. For instructions, see the following link and section: “Add local web service URLs as SPNs in Azure AD”:
https://docs.microsoft.com/en-us/office365/enterprise/configure-exchange-server-for-hybrid-modern-authentication
ThomasStensitzki-MVP The local exchange is addressed via a load balancer (KEMP Loadmaster). Inquiries to EWS etc. are passed on.
The HCW has filled out the TargetAutodiscoverEpr automatically.
from EXO to on premises and from on premises to EXO.
However, I have only tried it with registered target sharing EPR, but this did not lead to success.
AtanasM I'd recommend the following steps for troubleshooting this further:
- Use Exchange RCA to verify that free/busy is working fine (https://testconnectivity.microsoft.com/Default.aspx?testId=freeBusy)
- (Re-)Check the OAuth configuration of Exchange Server (https://docs.microsoft.com/en-us/exchange/configure-oauth-authentication-between-exchange-and-exchange-online-organizations-exchange-2013-help)
If there are multiple Exchange Server in the DAG, ensure that the AutoD- and EWS-vDir configuration is consistent across all servers - Are there any authentication error (401) entries in the IIS front-end logs, as shown in this post (https://c7solutions.com/2014/08/exchange-online-freebusy-issues-with-oauth-authentication)
This is an older post, but still helpful - Did you check the Exchange Server's EWS and Availability Service (AS) logs?