Error code: 15 Let's Encrypt Support

[morais]

What causes the error → Error code: 15 on SSL immission. Lets Encrypt Support.

[isscbta]

Please verify that the domain you wish to secure with SSL is correctly pointing to your server's IP address for both the '@' (root) and 'www' records - https://dnschecker.org/

[ebk]

I've the same error for Let's Encrypt (Error code 15) on a subdomain, but another subdomain and main domain works fine

My actual setup is:

subdomain1.example.com -> subdomain to access MyVesta
PHP FPM 7.4
Proxy support NGIX with template hosting-webmail-phpmyadmin
SSL Support with Let's Encrypt works

example.com (and www.example.com) -> CMS installed
PHP FPM 7.4
Proxy support NGIX with template hosting
SSL Support with Let's Encrypt works

subdomain2.example.com -> Nextcloud installed that it's not working fine
PHP FPM 8.4
Proxy support NGIX with template hosting
Cannot activate SSL Support with Let's Encrypt because it gives me Error code 15

Change php version on subdomain2 doesn't solve the problem.

Can someone help me to figure out the solution?