We are running Presence 7 with CUPC 7. We have 2 nodes in our Presence cluster. We initially configured the cluster as load-balancing, but CUPC users were failing to login to the secondary server, so we switched to an active-standby model.
Once users log in the first time to CUPC, I believe it downloads a server list and determines which node the user should be logging into. When the user logs in the second time, it specifies the secondary server as the login server and the user fails to log in.
As mentioned, we've switched over to active-standby to workaround the issue. I've checked all services running on both servers and they are the same.
Both servers are in DNS.