I have the same problem. Trying to connect an ipad running ios 13 from a Macos Catalina to another Macos Catalina. Both the machines are in the same LAN and have all ports open between them. The iPad is visible in the list of devices in NoMachine, but when i connect, it gives the loading indicator for about a minute and then shows the red icon for the error.
Is there any log file i can check?
Thanks, Sunny