So what happens there is on the VPS (not OVH) you’re telling Let’s Encrypt, “I promise I am chathizpano.com and www.chathizpano.com”, and so Let’s Encrypt connects to those names over HTTPS to attempt the tls-sni-01 challenge, but instead of reaching the standlone Certbot you’re running, Let’s Encrypt reaches the OVH web servers you have, and those say “No, we don’t know anything about this, it’s not us” and so you can’t get a certificate for those names.
This is of course necessary as otherwise anybody could get certificates for your names. You need to pass a challenge for the names you want on the certificate, you must arrange to pass one of three kinds of challenge, perhaps for you it will be easiest to pass DNS challenge?
But it seems odd to want the VPS to have certificates for these names, while having OVH answer actual requests for those names. Maybe it will be easier for someone to help if you explain what you wanted to achieve there…