I was troubleshooting a strange problem with Exchange 2010 public folder calendars and Outlook 2010.
The normal operation was:
User added a public folder calendar to favorites and that Calendar was then automatically added to Other Calendars in Outlook.
The symptoms that started this troubleshooting was that users complained that the “connections” to shared public folder calendars was missing each time Outlook was restarted. In other words: the calendars disappeared from Outlook and needed to be manually added again.
I found out that the connection in “Favorites” still was active. And if I opened the calendar from favorites again, the calendar was added in the shared calendars again… Strange. I also saw that opening Public folder opening was pretty slow.
When looking at connections status from Outlook client, I saw that the Outlook client was connecting to wrong public folder server. In another AD site across WAN.
I started some traces, and found out that the Outlook client tried to connect to correct server but timed out. And after the time out, Outlook successfully connected to wrong server.
The CAS role was installed on a separate server, so I could restart some services on back-end server without interrupt the Outlook clients.
I know that the RPC Client Access service on the mailbox servers is used for public folder access on Exchange 2010. I was unable to restart the service, it could not be stopped. I needed to kill the service and then start it again. After this the Outlook could connect to correct public folder server. And guess what, the public folder calendar was not disappearing anymore.