Over the weekend, we moved all of our room mailboxes over to Exchange. For users who have lots of room calendars open in their Outlook clients, they are getting the error message "Cannot Open the free/busy information. You Server Administrator has Limited the Number of Items You Can Open Simultaneously" after the migration from Exchange 2010.
Restarting the Outlook client temporary fixes the problem, but the problem comes back after they access the calendars again.
The users impacted deal with a lot of room scheduling, so they have 30+ room calendars open in their Outlook clients.
I have tried setting up a throttling policy with unlimited RCA connections, but that didn't help.
I have seen with Exchange 2010 there were some registry keys people were setting on the server that pretty much makes everybody have unlimited connections, but that isn't ideal if's only affecting a few people.