I ran into the following errors when trying to start another Xfce session for VNC while an existing one was already running.

/usr/bin/startxfce4: X server already running on display :1
Unable to create /home/niklaas/.dbus/session-bus
Xlib:  extension "RANDR" missing on display ":1".

When writing Ansible playbooks, it makes sense to test them on vanilla systems. This way you can ensure that what you wrote actually works and you do not forget any prerequisites your playbook requires. A testing environment can be set up with Vagrant easily, as described in the following post.¹

In some cases it makes sense to install upgrades of packages automatically. This can reduce time for maintenance a lot. To do so, install the little helpers unattended-upgrades and apt-listchanges with the following command:

Accessing your computers from remote at home isn't easy since you lack a public IP address in most cases. A workaround is to use a server with a public IP address as an entrance to a meshed tinc virtual private network (VPN).

Syncthing is a great tool for keeping machines in sync. This is quick write-up on how to configure automatic start with systemd on server. Important: This is different from setting it up on a client machine. In this case you would run it as the user logged in.