Getting 'Network connect error' when trying to establish a KVM session on 2161AD

We recently bought a Remote Access Key for a Dell 2161AD KVM that we have.

I can log in to the KVM and see the attached devices and they are all showing as Idle.

When I click on any of the 'KVM Session' links, the web browser downloads a java app which pops up a dialog box asking 'Do you want to run this application?'. I click the 'I accept the risk...' box and then the Run box.

I then get a pop up saying 'Connecting to <server>' followed immediately by a pop up saying 'Network connect error'

I've upgraded the KVM firmware to 1.14.01.

I've also installed the latest version of RCS (4.1.2.1) and that doesn't connect either.

Running a packet trace from my PC, I can see that it is connecting to port 2068 (avauthsrvprtcl) on the KVM and after a few packets are exchanged, the KVM resets the connection.

Any/all help will be much appreciated.

Michael.