If the on-premises Exchange organization can successfully connect to Exchange Online, you may receive the following error:
server ---> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond IP_Address:443
at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)
If the direction from Exchange Online organization to the on-premises Exchange organization is successful, the Free/Busy information works only from a cloud user to an Exchange on-premises user.
Article ID: 3137585 - Last Review: 15 Mar 2016 - Revision: 1