Certbot failed to authenticate some domains (authenticator: nginx)

[Joaquin]

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is:
krill.egihosting.com

I ran this command:
sudo certbot --nginx

It produced this output:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Requesting a certificate for krill.egihosting.com

Certbot failed to authenticate some domains (authenticator: nginx). The Certificate Authority reported these problems:
Domain: krill.egihosting.com
Type: dns
Detail: no valid A records found for krill.egihosting.com; no valid AAAA records found for krill.egihosting.com

Hint: The Certificate Authority failed to verify the temporary nginx configuration changes made by Certbot. Ensure the listed domains point to this nginx server and that it is accessible from the internet.

Some challenges have failed.
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /var/log/letsencrypt/letsencrypt.log or re-run Certbot with -v for more details.

My web server is (include version):
nginx version: nginx/1.18.0 (Ubuntu)

The operating system my web server runs on is (include version):
Ubuntu 22.04.2 LTS

My hosting provider, if applicable, is:
self

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

I'm using a control panel to manage my site (no, or provide the name and version of the control panel):
no

The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot):
certbot 2.6.0

Additional:
DNS-01 Challenge passes: Let's Debug
dig shows no issues: Dig (DNS lookup)

[_az]

10.23.27.63 is a private IP. It can only be accessed from inside your internal network, which means that Let's Encrypt (and anybody else on the internet) is not able to connect to your web server.

certbot --nginx uses the HTTP challenge, which isn't going to be possible for you, unless you use your public IP and port forward port 80 on your public IP to your nginx server.

You can try use the DNS challenge, but unless your domain's DNS host has some form of API/automation, it probably won't be possible to do automatic renewal. You can try with:

certbot certonly --manual -d krill.egihosting.com --preferred-challenges dns