GNOME 3.20 on Ubuntu 16.04 through VNC on AWS

Question

I want to access my AWS EC2 instance (Ubuntu 16.04 LTS) through VNC using a GNOME3 GUI, but the GUI I get looks very old. What am I doing wrong?

I started with a fresh EC2 instance and installed GNOME3 like this:

sudo add-apt-repository ppa:gnome3-team/gnome3-staging
sudo add-apt-repository ppa:gnome3-team/gnome3
sudo apt update
sudo apt dist-upgrade
sudo apt install gnome gnome-shell

After the GNOME install finished, the tutorials I read said I would get a prompt to use a display manager LightDM or GDM. I didn't get such prompt after/during the installation process.

I then tried to force the GDM3 install:

sudo apt-get install gdm And I installed a few other packages:

apt-get install gnome-panel gnome-settings-daemon metacity nautilus gnome-terminal

Then I installed the VNC server like this:

sudo apt-get install vnc4server

And I setup the VNC server and editing the startup file

vncserver
sudo vim ~/.vnc/xstartup

My startup file looks like this:

#!/bin/sh

export XKL_XMODMAP_DISABLE=1
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &

gnome-panel &
gnome-settings-daemon &
metacity &
nautilus &
gnome-terminal &

And then I restart the VNC server:

vncserver -kill :1
vncserver -geometry 1600x900

So after all this, I login through TightVNC on Windows and this is what it looks like:

This is definitely not the nice GNOME3 interface. What am I doing wrong?