"Failed to Connect to Clientname" when trying to add an Exchange Cluster Client (94810)

When trying to configure/setup an Exchange Cluster Client, after entering the correct information... you get an hour glass for a while, before you get the pop up showing that it Failed to Connect to <Clientname>

The issue, other than the obvious of wrong information... so please verify first, is when there is a Firewall involved and there are no rules allowing the Exchange Application IP address and the Backup Server to communicate bi-directionally.

Workaround:

1. Turn off the firewall.

or

2. If that is not an option, create a rule within your Firewall to allow the Exchange Application IP address to communicate within your Domain

You will need to allow your Backup Server to do the same otherwise your server will be waiting for a response from the Exchange Application IP and never get a response, and vise versa. You will just get an hour glass, and eventual failure to add/create the Cluster client.