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My domain is:
Cannot reveal

I ran this command:
certbot certonly --standalone -d my.domain.com

It produced this output:

  • The following errors were reported by the server:

    Domain: my.domain.com
    Type: connection
    Detail: Failed to connect to 123:.456.789.123:443 for TLS-SNI-01

My operating system is (include version):
Debian 8

My web server is (include version):
node.js/express (which is not running)

I can login to a root shell on my machine (yes or no, or I don’t know):

My iptables allows all outgoing traffic, and all incoming on port 443.

Are you behind some sort of router which needs a portmap for port 443?

are you intending to use the TLS-SNI challenge?

if so do you understand how that challenge works?

open port 443 in yor firewall:
ufw allow 443/tcp


This solved our renewal issue as well, thanks @nickleus!

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