Sorry, Peter, my fault. RealVNC is not (yet) compatible with Ubuntu 18 based systems.
Here the instructions I found for installing VNC on OS 18 systems:
linuxconfig.org/vnc-server-on-ubuntu-18-04-bionic-beaver-linux
Please note, I have not yet tried this. I am holding out until I REALLY have to "upgrade", knowing full well that it will probably take me a couple of hours at least to unbreak my system again.
Greetings from Ubuntu 16.04.....
Jo

If vnc is using port 22, it means there's a special configuration to have it go through ssh. There should be documentation to explain the default.

I'll just describe my own setup. I installed TigerVNC because the documentation is simple and clear. I have automatic login enabled, and x0vncserver configured to start in the background in the user profile. I configured the vnc password for my local user with vncpassword. The connection port is the default 5900, and there is no further security involved than the WiFi connection, and the VPN when accessing the computer from outside my local network.

I had this use case planned from the beginning, and I must admit I was quite angry against most vnc packages only documenting the unintuitive full-vnc user session. That is only useful for multi-user servers, not in our situation where we configure the system with a screen connected, then move it headless to the telescope setup.

EDIT: TigerVNC is only available on arch x86, I just wanted to describe my setup, in case the issue is configuration.

-Eric

Yah, I just got an email from RealVNC: Linda RealVNC (RealVNC) that stated "Unfortunately, we only support the Raspberry Pi on the ARM chips."

I think that only applies if you are using Raspbian as your OS.

Since you are using Lubuntu, the regular *Linux-x*.deb installation file is what you would want.
Regardless, RealVNC may only be compatible with 16.04 LTS+, it does not mention 18.04.

If you can't install it via the .deb file
www.realvnc.com/download/file/vnc.files/...-6.3.1-Linux-x64.deb (64-bit version)
www.realvnc.com/download/file/vnc.files/...-6.3.1-Linux-x86.deb (32-bit version)
that's where the problem likely lies.

Unless...
Did you try those or did you try installing the Raspbian (ARM) version? That may not work.
I am also running RealVNC on my Raspberry Pi3 and since I am using Ubuntu MATE on it, I think I had to install the Linux-x64.deb version, NOT the Raspbian version, on it.

I downloaded both of those files above, and when I launch them the installer says "incorrect architecture".
PK

In that case I may have been mistaken. Since I am away from home, I can't check which version I actually have on my Pi3. Sorry if I wrote something misleading here. I do remember that I also went through this by trial and error, but in the end everything worked fine.
Jo

I am not installing on a Pi3, but a NanoPC T4 which uses a RK3399 cpu.

Got it. I was just saying that if your nanoPC uses the ARM architecture, then my statement that I installed a non-ARM version of RealVNC on my Pi3 was likely incorrect. I needed to amend that before someone else gets misled.

If you can't solve the vnc issue, you can go another way and use X11 ssh forwarding to get the remote session displayed on your Mac.

That should be relatively basic steps: installing the X Server port "XQuartz" on your Mac, using a terminal to login to the nanopc via "ssh -X user@ip", and launching commands from there. Apps will display their interface on your Mac.

-Eric

tightvnc seems popluar, I run vnc4server, but I couldn't find any thing specific for your combination.
This is a bit off the wall, but this blog might be a resource for you.
tech.scargill.net/nanopc-t4-from-friendlyarm/#more-9931
He just got his nanopc-t4 & install lubuntu and last post had run into your dbus issue.
Could let him know the fix and ask him which vnc server he is using.
/Tom

I use the vino VNC server on Ubuntu and the RealVNC client (the free one!!!) on my Mac. Vino needs to not be encrypted for this to work. By the way, I use the RealVNC client on my iPad as well and that works too.

Mde lots of progress tonight. I got Vino VCN to work, and connects from a local network well. Very responsive too.
But - I have two issues I need help with:

1. I need the system (Lubuntu) to start the VNC server automatically upon startup. As the machine will be headless, it needs to be a turnkey system. I'm not sure if Vino Vnc will allow that. If not, please suggest an alternative, noting that RealVNC does not work on the NanoPC T4.

2. As soon as I log off from my Mac, VNC server shuts down on the Lubuntu machine. I need it to stay active all the time.

Any help would be appreciated!

Peter