To get Ubuntu desktop accepting RDP connections, you must first install and enable Xrdp tool… to do that, run the commands below

sudo apt install xrdp
sudo systemctl enable xrdp

After running the commands below, logout or reboot your desktop.

Now that Xrdp server is installed, go and open Windows Remote Desktop Connection app and connect to the server IP or hostname…

CAUTION:

Update

I have read all the comments below… and tried again was successfull… Here’s the trick..

1. Make sure you’re not already logged on to the Ubuntu desktop… best thing is to restart and don’t logon
2. If you try Xorg session and it quickly disconnect… select the X11rdp from the drop-down list.. it will hang and not fully logon… close the session and try the Xorg session again… that time it will work… but keep prompting you to authenticate… you can cancel the prompt windows…
3. Restart again if step two doesn’t work right away..

/etc/netplan/01-network-manager-all.yaml

# Let NetworkManager manage all devices on this system
network:
  ethernets:
    enp1s0:
      addresses: [10.133.229.234/24]
      gateway4: 10.133.229.1
      dhcp4: no
      nameservers:
        addresses: [10.133.144.249,10.133.144.248]
      optional: true

  version: 2
  renderer: NetworkManager

https://www.binarytides.com/remote-ubuntu-desktop-via-vnc/

its name is vnc4server while previous named as vino-server.

1.first install the server:

sudo apt-get install vnc4server

2.then close original vino service:

just open remote desktop sharing and uncheck the first checkbox "Sharing"-->"Alloow other users to view your desktop"

3.config an login passwrod by typing:

vncpassword

no "sudo" is needed

4.start vnc service:

vncserver -geometry 1920×1280 -alwaysshared :1

-geometry indicates the screen definations, here is 19201280, the "" is "x" but not the operator multiple

-alwaysshared allows more than one user to login to one desktop

:1 is just the id you named for this remote desktop, you can use :1 to connect to this desktop

after the service started, an ".vnc" folder would be generated under current user directory:

/home//.vnc/

modify xstartup file under this folder:

mark the line "twm &" with "#",

and add gnome-session &

save and exit.

5. try to connect to the VNC server by VNCViewer or others