I've been trying to work with F5 about this issue, but I occurs to me that it might be time to try it from another angle.
I have an F5 BigIP HA pair and the active node is running 10.2.3 (hereby known as Node2) and the standby node is running 11.4.0 (hereby known as Node1). The standby node was running an exact copy of the configuration on the active node prior to upgrading the system and the upgrade completed without error.
What's happening is when I make Node1 the active node so as to upgrade Node2, it disconnects our Viewconnect server from the network. Now the Virtual Server on the BigIP and the Pool and Node are identical to their counterparts on Node2, but traffic does not get passed and all users receive connection errors when they attempt to log onto their virtual machines. Also, the Viewconnect server cannot respond to pings to either the DSN name or IP address. If I fail back, everything works just fine.
Does anyone have any idea what's happening? This is a time-sensitive issue.