Can you attach the screenshot which didn’t attach? Don’t paste, but use the attachment tool “Upload attachments”.
Also, tell us:
– did you update from an earlier NoMachine version?And what version are you using now?
– specify the OS client side and also server side.
In NoMachine version 8, UPnP/NAT-PMP is disabled by default in the Free Edition. To get access to your computer over the internet, NoMachine’s UPnP/NAT-PMP port mapping must be enabled by hand (‘Server settings -> Ports’ -> Select the service and click on Configure); or alternatively, your router can be configured with the appropriate port-forwarding rule.