If you’re already troubled with varnish on changing listening ports from default. Here’s a little hack that worked on my Debian and Ubuntu distribution.
sudo apt remove varnish
sudo apt-get purge varnish
# I manually remove the 3 files in created in /etc/systemd/system/*
sudo apt install varnish
sudo nano /lib/systemd/system/varnish.service # put the rigth conf
sudo nano /etc/varnish/default.vcl #put the rigth conf
sudo systemctl daemon-reload
sudo service varnish restart
