I created a fresh Drupal site and I downloaded and installed the Domain Access module.
I created a first subdomain which has the same hostname as the default Drupal host. In my case: multisitedomain.dd:8083. This subdomain works fine.
I created a second subdomain with the following host:
sub.multisitedomain.dd:8083. This subdomain does not work and launches a 404 Not Found error when accessing it.
I tried also tried enabling the extension in the cookie domain located in
/sites/default/services.yml and to add the extension to etc/hosts and to vhosts.conf as suggested here.
Nothing of this works and the Not Found error still shows up.
What can it be?