On: now new problems 
> ./letsencrypt-auto certonly --standalone -d nextechanisme.com -d www.nextechangisme.com
Updating letsencrypt and virtual environment dependencies.......
Running with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt certonly --standalone -d nextechanisme.com -d www.nextechangisme.com
Failed authorization procedure. nextechanisme.com (http-01): urn:acme:error:connection :: The server could not connect to the client for DV :: Server failure at resolver
Any idea ?