I recently changed desktop environments on Linux, and found that my choice didn't render really well through xrdp and rather than figure it out, I wanted to try the screensharing option in the Ubuntu 20.04 system settings.

However, when I went to enable it, I found the following error in syslog:

May  6 15:49:08 boris gnome-control-c[64701]: message repeated 3 times: [ Failed to enable service vino-server: GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Sharing cannot be enabled on this network, status is '0']

This is a known bug in this GNOME package when your network interface Vino would be binding to is managed by systemd-networkd. You can see which interfaces are currently managed using the networkctl command:

jdmarhee@boris /etc/netplan $ networkctl
IDX LINK       TYPE     OPERATIONAL SETUP    
  1 lo         loopback carrier     unmanaged
  2 eno1       ether    routable    managed
  3 tailscale0 none     routable    unmanaged
  4 docker0    bridge   no-carrier  unmanaged

4 links listed.

where eno1 was being managed. In Ubuntu 20.04, the network interfaces are configured using netplan. The systemd-networkd backend is the default for doing this, so I needed to update netplan to use NetworkManager instead. Your config will be in a file like this one in /etc/netplan:

jdmarhee@boris /etc/netplan $ cat 00-installer-config.yaml 
# This is the network config written by 'subiquity'
network:
  ethernets:
    eno1:
      dhcp4: true
  version: 2

and add the following under network key to specify the backend (I add it right under the version):

  renderer: NetworkManager

and then apply:

sudo netplan apply

You can then verify that that interface is no longer managed:

jdmarhee@boris /etc/netplan $ networkctl
IDX LINK       TYPE     OPERATIONAL SETUP    
  1 lo         loopback carrier     unmanaged
  2 eno1       ether    routable    unmanaged
  3 tailscale0 none     routable    unmanaged
  4 docker0    bridge   no-carrier  unmanaged

4 links listed.

and should be able to enable Vino without issue (amongst other preferences that rely on the interface not being managed by systemd).