Found the problem!  We had port expanders from the 2161DS switch this was replacing still in place.  Removing these, the servers can find the virtual media now!  Now onto finding replacement port expanders.
We recently purchased and setup a 2162DS to replace our older 2161 KVM specifically to add virtual media.  We also purchased a number of USB2 virtual media server modules. However, we cannot get the virtual media to map to the servers.  The servers will detect that a CDROM drive is present, but never detects and media in the drive.  The client software shows 0 for read bytes at all times.   We verified that the network has access to ports 2068 and 3211, tested with different operating systems, tested using an ISO or a real CD, tested a USB cd connected directly to the KVM, same effect in all cases.  Any other ideas?  Thanks, Matt
2162DS Virtual Media Not Mapping