There are two main reasons why Let’s Encrypt might not be working::
1.- Make sure port 80 an 443 is not blocked by the firewall.
2.- If you have installed the GeoFirewall module, do not block the USA, since the let’s Encrypt server needs access to create or renew the certificate and these servers are generally in the USA.
3.- Make sure that your domain’s DNS records are already pointing to the public IP of your server.
If you cannot enter the interface because the certificate expired and it cannot be renewed, we recommend doing a configuration reset and re-creating the certificate from the interface. For this we use the following command from the console:
vitalpbx --reset-apache-conf