After a bit more tinkering around, the cluster appears to have no more communication issues. I checked the /etc/hosts file and although all of the FQDNs were present for all nodes, what I noticed is that a 127.0.0.1 FQDN had the same description as some other FQDNs For example:

127.0.0.1 slavenode1 slave1
192.168.##.### slavenode1 slave1

After removing this extra FQDN, I believe the communication could work fine... the nodes now showed the correct IP address which had all the proper ports forwarded.