I’ve just installed the free version of NoMachine on Ubuntu 19.04 (vanilla) and on Arch Linux (KDE Plasma 5.16.4), both physical.
I can access Ubuntu from Arch, but not Arch from Ubuntu.
When I try to access Arch from Ubuntu, I can see the “User e connected” notification on Arch, but then on Ubuntu the following message immediately appears: “The connection with the server was lost. Error is 104: Connection reset by peer.”
I’m using default settings and no VPN or proxy.
I’ve attached the session log (here I created a manual connection, but the same happens with the auto-detected one).