I've running isp config 3.2.7p1. I added a new website with SSL and Let's Encrypt SSL options selected. web site created but there were no ssl. I tried to select SSL and Let's Encrypt SSL options again but nothing happened. it was working before but I didn't add new website for a long time. firewall seems ok, dns records seems ok. what might be the problem?
When your server is behind a NAT router so that the server itself can not reach the hosted domains, then enable the option "Skip Letsencrypt check" under System -> Server config -> server1.example.com -> Web. this worked.