I wanted to extend the SSL certificate to my subdomain. My server is on debian 8.0 (jessie) and I got this error:
Failed authorization procedure. cloud.domain.ltd (tls-sni-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Failed to connect to 18.104.22.168:443 for TLS-SNI-01 challenge IMPORTANT NOTES: - The following errors were reported by the server: Domain: cloud.domain.ltd Type: connection Detail: Failed to connect to 22.214.171.124:443 for TLS-SNI-01 challenge To fix these errors, please make sure that your domain name was entered correctly and the DNS A record(s) for that domain contain(s) the right IP address. Additionally, please check that your computer has a publicly routable IP address and that no firewalls are preventing the server from communicating with the client. If you're using the webroot plugin, you should also verify that you are serving files from the webroot path you provided.
Here how, I configure my subdomain with apache in the file cloud.subdomain.ltd.conf:
<Virtual Host *:80> ServerAdmin firstname.lastname@example.org ServerName cloud.domain.ltd DirectoryIndex index.html index.php DocumentRoot /var/www/cloud.domain.ltd/owncloud Alias /owncloud "/var/www/cloud.domain.ltd/owncloud/" <Directory /var/www/cloud.domain.ltd/owncloud/> Options +FollowSymlinks AllowOverride All <IfModule mod_dav.c> Dav off </IfModule> SetEnv HOME /var/cloud.domain.ltd/www/owncloud SetEnv HTTP_HOME /var/www/cloud.domain.ltd/owncloud </Directory> ErrorLog /var/www/cloud.domain.ltd/logs/error.log CustomLog /var/www/cloud.domain.ltd/logs/access.log combined </VirtualHost>