It produced this output:
Obtaining a new certificate
Performing the following challenges:
tls-sni-01 challenge for restosducoeur75.ddns.net
Enabled Apache socache_shmcb module
Enabled Apache ssl module
Waiting for verification…
Cleaning up challenges
Failed authorization procedure. restosducoeur75.ddns.net (tls-sni-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Connection refused
I can telnet my web server from everywhere local/internet. It is the default raspian 9.1 stretch installation, I didn’t check if there is a firewall or not. I will
It is not easy to find prerequisites. As for Apache it is using tls, I have to allow 443 and 80. Do I need to have my own telnet server or is certbot shutting down web/telnet itself and using its own servers ?
So it looks that raspbian has not a firewall, and I configured my routeur to forward 80 & 443 port to my web server. 80 is working perfectly. I get wrong, telnet is using 23 not 443, sorry for the mistake but 443 was already forwarded.
I tried with “certbot-auto --apache”, I have the same error