Port 80&443 Connection Refused (CURL)

Nextcloud version: 18.0.3.0
Operating system and version: Debian 10
Apache or nginx version: Apache/2.4.38
PHP version: 7.3.13

The issue you are facing:
Website is completely fine at Port 80 & 443. But I also need access via CURL. My other instances on the same Server and Ports are working fine on CURL. I just get the message with CURL:
Failed to connect to cloud.barner.online:443 : Connection refused
I already checked the Virtual Hosts but nothing unusual there.

Is this the first time you’ve seen this error? (Y/N): Y

The output of your Nextcloud log in Admin > Logging:
Nothing about this topic.

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php
$CONFIG = array (
  'instanceid' => '********',
  'passwordsalt' => '**********',
  'secret' => '********',
  'trusted_domains' => 
  array (
    0 => 'cloud.barner.online',
  ),
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'datadirectory' => '/mnt/data/nextcloud/',
  'dbtype' => 'mysql',
  'version' => '18.0.3.0',
  'filelocking.enabled' => false,
  'overwrite.cli.url' => 'http://cloud.barner.online',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'nextcloud',
  'dbpassword' => '********',
  'installed' => true,
  'maintenance' => false,
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_from_address' => 'noreply',
  'mail_domain' => 'barner.online',
  'mail_smtphost' => 'mail.barner.online',
  'mail_smtpport' => '465',
  'skeletondirectory' => '',
  'force_language' => 'de',
  'knowledgebaseenabled' => false,
  'theme' => '',
  'loglevel' => 2,
  'updater.release.channel' => 'stable',
  'app_install_overwrite' => 
  array (
    0 => 'rainloop',
    1 => 'loginviapost',
  ),
  'mail_smtpauth' => 1,
  'mail_smtpname' => 'noreply@barner.online',
  'mail_smtppassword' => '********',
  'mail_smtpsecure' => 'ssl',
);

The output of your Apache/nginx/system log in /var/log/____:
Just other problems from other Threads.

Virtualhost (443/SSL)

<IfModule mod_ssl.c>
<VirtualHost 173.212.231.239:443>
ServerAdmin malte@barner.online
ServerName cloud.barner.online
ServerAlias cloud.barner.online
DocumentRoot /var/www/barneronline/nextcloud
    <IfModule mod_headers.c>
      Header always set Strict-Transport-Security "max-age=15552000; includeSubDomains"
    </IfModule>
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined

SSLCertificateFile /etc/letsencrypt/live/cloud.barner.online/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/cloud.barner.online/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
</VirtualHost>
</IfModule>

Virutalhost (80)

<VirtualHost 173.212.231.239:80>
ServerAdmin localserver@localhost
ServerName cloud.barner.online
ServerAlias cloud.barner.online
DocumentRoot /var/www/barneronline/nextcloud
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
RewriteEngine on
RewriteCond %{SERVER_NAME} =cloud.barner.online
RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
</VirtualHost>