SYMPTOMS
When I try to access non existing domain in Plesk or the new domain that still has default Plesk "index.html" page, the page is loading for several minutes.CAUSE
Plesk default index.html page contains JavaScript code that connects to 8880 port on Plesk server to get news. In case if this port is not accessible, some browsers show the page as loading while the timeout occurs.RESOLUTION
Make sure that port 8880 is opened on the Plesk server and you can access it from the outside. The list of ports that are required by Plesk can be found in the corresponded article.Or you can replace default Plesk index pages with own ones. The pages should be replaced in skeleton directories:
/var/www/vhosts/.skel/*/httpdocs/index.html
/var/www/vhosts/.skel/*/httpsdocs/index.html
And for the default domain:
/var/www/vhosts/default/htdocs/index.html
/var/www/vhosts/default/httpsdocs/index.html
Note, the path to 'vhosts' folder differs for different OSes, see the HTTPD_VHOSTS_D variable value in /etc/psa/psa.conf to find it.