We are migrating from an exchange Server 2007 infrastructure to exchange 2013.

Our 2013 setups consits of two mailbox servers and two separate CAS servers running exchange 2013 CU8 and Windows Server 2008 R2. Whenever the active node is shut down the databases fail over to the other server in the DAG. No issues with this.

The issue is that whenever I shut down the second CAS server, all users get disconnected from outlook. It will either say disconnected, limited connectivity or just "trying to reconnect" which it never does until I bring that second CAS server back online.

But Outlook Web stays connected just fine at all times. So the issue is with the desktop client. All the virtual directories are pointing to the right URL( the load balancer VIP)

I've compared the settings/roles/services between both CAS servers and everything is exactly the same.

I'm at wit's end and hoping for some answers from some of the more knowledgeable and experienced members of this community.

• Edited by OneITGuy2015 15 hours 28 minutes ago

Since OWA is working fine, i suspect the problem is with the MAPI/HTTP (provided you have Outlook 2013. If not then it will be RPC/HTTP) settings on the other CAS server. Could you please verify/compare the this specific settings on both the CAS server ?

reference links

http://port25guy.com/2014/03/01/how-to-enable-mapi-over-http-mapihttp-in-exchange-server-2013-sp1/

https://4sysops.com/archives/outlook-anywhere-for-exchange-2013/

https://technet.microsoft.com/en-in/library/dd638082(v=exchg.150).aspx

https://technet.microsoft.com/en-us/library/dn635177(v=exchg.150).aspx