My assumption is that this is a physical appliance and that the public and private networks have similar IP schemes, which may be having DCE use its private proxy for connection. If this is a physical appliance, please provide the IP schemes of the public and private from within the DCE desktop client under: System > Server Administration Settings > Network Settings. Provide a screen capture of Public (LAN1) and Private (LAN2) [both Network A and Network B tabs].
The DCE privateproxy does not allow certain code types through such as activeX, and therefore some interfaces may not load properly, which may be the case here. The first step though is finding out why DCE is using a private proxy.
If there is no Private LAN2 tab, then the private proxy should not be used at all and you will need to work through local escalation to log and troubleshoot the issue. Also if there is a Private LAN2 tab, but it is on a different network scheme such as a 10.X.X.X network, then you will need to work with local esclation as well, as the private proxy should not be used to connect to the 192.168.X.X network, especially if those devices are connected to the GB1 (Public LAN1) port on the server.
I have also seen where customers try to use the Private LAN2 tab as the Public LAN, which can cause issues such as this. If there is no Private network the GB1 port on the server should be the only port being used. If virtual, there should not even be a 2nd NIC added to the VM, and therefore no Private LAN2 tab displayed within the Desktop Client.