Domain that redirects to HTTPS shows Default webserver page (default apache page)
SSL apache port is missing in domain's configuration files:
# httpd -S | grep example.com.conf | egrep '443|7081'
Domain is coded this way to redirect all requests to HTTPS (443 port is used for HTTPS when nginx is diabled and 7081 is used for HTTPS when nginx is enabled), but SSL support is disabled for a domain.
Enable SSL support for a domain: Domains > example.com > Hosting Settings > SSL/TLS support