Redirect all hostnames to the panel hostname (cpcmd scope:get net.hostname) using a mod_rewrite redirect.

Add the following to /usr/local/apnscp/config/httpd-custom.conf

<Directory ${APNSCP_ROOT}/public>
RewriteEngine on
RewriteOptions inherit
RewriteCond %{HTTP_HOST} ^([^:]+)
RewriteCond "%1 %{ENV:HOSTNAME}" "!(^[^ ]*) \1"
RewriteRule ^(.*)$ %{REQUEST_SCHEME}://%{ENV:HOSTNAME}:%{SERVER_PORT}/$1 [R,L]
</Directory>

Then restart ApisCP,

systemctl restart apiscp