Perfect server installation ISPConfig 3.1, Ubuntu 18.04

https://www.howtoforge.com/tutorial/perfect-server-ubuntu-16.04-with-apache-php-myqsl-pureftpd-bind-postfix-doveot-and-ispconfig/
"The ISPConfig 3.1 version that is used in this tutorial is currently in beta" - checked. Now relseased.

Before starting :
# adduser thomas
# adduser thomas sudo

hostname : server1.example.com -> vps7.clight.fr
IP address : 192.168.1.100 -> 51.75.78.134
gateway : 192.168.1.1 -> 51.75.64.1 (found with command : route -n)

When asked for passwords to MySQL I use machine SWA...

This how-to starts assuming basic minimal installation of Ubuntu 16.04
Now using nano instead of vim

5. Synchronize the System Clock - > SKIP THIS

7.1 Install Metronome XMPP Server (optional) - SKIPPED

11. Install PureFTPd and Quota

#nano /etc/fstab

SKIPPED

18.2 OpenVZ

AT THE END :

1) Change the time zone to Paris : dpkg-reconfigure tzdata