The external ip is correctly configured (I can access all other web applications installed on my PI when the VPN is off).
The port is ok in the router forwarding (used the default 51820, TCP protocol).
I tried changing the DNS in the phone app to 8.8.8.8 but to no avail.
Could I have made something wrong with pivpn installation/configuration wizard? Is there a way to reset it from the start?