I have a question regarding setting up a heartbeat between two nodes on a cluster (In this case Windows Server 2012) when the nodes are on separate physical sites connected over a WAN. When the public NIC's can ping each other and theheartbeat cannot, what usually is the issue? When I run the cluster validation test I get the following result: Network interfaces SERVER01 - Heartbeat and SERVER02 - Heartbeat are on the same cluster network, yet address 10.0.36.20 is not reachable from 10.0.36.15 using UDP on port 3343. I've checked the firewall on each server and port 3343 is open. I've asked the netadmin who oversees the Cisco router configurations whether port 3343 is blocked or not and he assures me it is not. Any ideas and suggestions will be appreciated.