If the distributed system is built on the basis of a network in which Servers and/or Clients are behind NAT, then VPN technology is to be in use for the operation of such system.
When you configure NAT the ports that are used by started INTELLECT™ modules are to be opened — see The list of TCP ports used in INTELLECT™ section. Moreover the ports that are used by MS SQL Server for database synchronization are to be opened.

If an ONVIF IP-camera is behind NAT, then proper operation of this camera is not guaranteed. This limitation is due to the special features of the ONVIF protocol.