Raspberry Pi 4B doesn't support Tigervnc server?

Hi everyone.

I just installed Ubuntu mate 20.04 on a Raspberry Pi 4B, I can install x11vnc server without any problem at all. But tigervnc server cannot work on it, from another pc's vnc viewer I can type in the vnc password but then it came up as "Connection has been gracefully closed". I need tiger vnc because it allows me to log in via vnc viewer as a different user on a independent display (virtual desktop), this is the steps that I followed:

https://www.server-world.info/en/note?os=Ubuntu_20.04&p=desktop&f=5

I saw some one made it work on Raspi 3 here:
https://ubuntu-mate.community/t/new-rpi3b-install-ssh-and-vnc-working-ok/21239

What about Raspi 4B then? Is it like Ubuntu mate 20.04 doesn't support tigervnc server on Raspberry Pi 4B yet? Anyone has any suggestions?

Thanks to the other user's post, I found the solution by installing Tightvnc server instead of Tigervnc server, this is the xstartup file that I used:

Sorry I forgot to mention this:

I had a grey screen in the first place and I have to install lxde according to this video. After that I realised that the xstartup is not incomplete but having too much content, so I changed my xstartup file to:

#!/bin/sh
#unset SESSION_MANAGER
#unset DBUS_SESSION_BUS_ADDRESS
xrdb $HOME/.Xresources
xsetroot -solid grey
#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
#export XAUTHORITY=/home/installer/.Xauthority
#/etc/X11/Xsession &
/usr/bin/mate-session &

IMPORTANT: if you still having the grey screen problem, please remember that your xstartup file needs to be generated not copied. To fix this problem, you can remove the xstartup file first and then start the vncserver, vncserver would create a new xstartup file for you. Modify that xstartup file and restart the vncserver, you'll be happy!