I'm having a strange issue. Currently I have Lync 2010 standard deployed in my environment. With the Lync client (v. 4.0) the automatic sign-in works fine. BUT, with my OCS R2 client, the automatic sign-in isn't working. Any idea why this might be?
The key to solving this issue was to enable logging in the OCS client, then looking at the log to see the exact reason OCS was unable to connect to the server.
After looking at my logs, I found that it was trying to connect to the public IP instead of the internal. These links were helpful with troubleshooting: