I was recently asked to look in to a Skype for Business 2015 infrastructure due to reported 2013 mobility client issues. The infrastructure consisted of a standard edition front end, edge server and KEMP load master reverse proxy. The issue was that mobility clients could not search for contacts and could not see certain status messages. All other features were working and users could chat/make calls.
Testing with https://www.testconnectivity.microsoft.com/ shows green across the board. If you are dealing with this issue, start with this tool and run the following tests:
- Skype for Business remote connectivity test
- Skype for Business autodiscover test
- Exchange server ActiveSync autodiscover test
Testing with Microsoft Lync Connectivity Analyzer showed ready for 2013 mobility client.
After examining the Lync Front End server event log, I found event 32054, LS Storage service:
Storage Service had an EWS Autodiscovery Failure. The underlying connection was closed. Could not establish a trust relationship SSL/TLS.
The issue would seem to be the published autodiscover Uri for Exchange not matching the installed certificate on the Exchange 2016 DAG members. The Uri in the event log was reporting autodiscover.domain.local. The certificates and all other services in the infrastructure were pointing to autodiscover.domain.org. On the Exchange server, running powershell Get-ClientAccessService | fl AutoDiscoverServiceInternalUri will display the currently assigned URLs.
Issuing a Set-CsClientAccessService -Identity exchange.domain.local -AutoDiscoverServiceInternalUri https://autodiscover.domain.org/Autodiscover/Autodiscover.xml for both servers in the Exchange DAG solved the mobility client address book issue.