In order to fix this on a WordPress site, first make sure your site is available over HTTPS (you might have to ask your host regarding this matter). If it is available over HTTPS, we recommend that you install the "Really Simple SSL" plugin. After the plugin setup, it may take up to 12 hours before the HTTPS/SSL error in the portal is resolved.

Apache
If you do not run a WordPress site, you can create a .htaccess file in the root of your website (or modify existing one) through FTP or a file manager in CPanel/WHM/Plesk and add the following (make sure to change the domain name on the last line):

RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.yourdomain.com/$1 [R,L]

nginx
It's a bit more technical to do this for nginx, as you probably need root access to modify the nginx webserver configuration settings.

The easiest way is to setup a listener for port 80 (HTTP), that redirects traffic with a 301 permanent redirect to the port 443 (HTTPS) listener.

Refer to https://zaiste.net/rewrite_http_to_https_in_nginx/ 

Did this answer your question?