I have discovered a slightly more detailed answer. The article is describing Azure deployment but it seems to address the NAT in more detail.
sk118133
Configure a Network Address Translation (NAT) rule in SmartDashboard in order to add the public IP address of the deployed machine to the supported servers list. This step is needed in order to make the Endpoint Security Server available outside the Azure network environment.
- Login to the Smart Endpoint Console.
- Select 'File > Manage > Endpoint Servers'.
- Highlight the NAT object and select "Edit", click "Next", then "Next" again.
- At this point, make sure the "Install Database Checkmarks" are all selected and select "Finish".
- After the Install Database completes you should install policy. You should see that your General Properties has updated and that the server list will be updated in the install policy window.
I think this more adequately describes how the clients are updated with the server listing (which should reflect the public IP)