Using NoMachine Network? You can skip this article. If you connect using the NoMachine Network service, there is no need to configure port mapping or enable UPnP in the NoMachine settings. The NoMachine Network service handles NAT traversal seamlessly. See the Getting Started with NoMachine Network tutorial for full instructions. 

If you are not using the NoMachine Network service and still wish to enable UPnP, read on. By default the automatic port mapping on the router is disabled in all NoMachine server products. To enable it, do the following on the target computer.

Open the NoMachine interface -> Settings -> Server -> Ports and select the nxd service, then click on Configure:

In the next panel, check the option 'Use UPnP to map the port on the gateway IP':

This should configure your router automatically for the external IP and the external port. Use them in the configuration of your NoMachine connections.

If the automatic port mapping fails, it is possible that UPnP or NAT-PMP is not supported by the router model, or it is not enabled on your router, or the router is behind another NAT router and you will have to configure the router manually. In that case, please refer to: https://kb.nomachine.com/AR04S01122