Redirect http:// to https://, http://www to https://

.htaccess

## https://www.reg.ru/support/hosting-i-servery/sajty-i-domeny/kak-dobavit-redirekt/redirekt-s-http-na-https
## вариант 1
RewriteEngine On
RewriteCond %{HTTPS} =on 
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [QSA,L]

## вариант 2
RewriteEngine On
RewriteCond %{SERVER_PORT} !^443$
RewriteRule .* https://%{SERVER_NAME}%{REQUEST_URI} [R,L]

## вариант 3
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

################################################################
## https://toster.ru/q/174797
RewriteCond %{ENV:HTTPS} !on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

################################################################
## https://bjoernfranzen.com/how-to-set-up-a-letsencrypt-ssl-certificate-for-your-wordpress-website-on-a-digital-ocean-server-managed-with-a-serverpilot-free-account/
RewriteCond %{HTTP:X-Forwarded-Proto} !=https
RewriteRule (.*) https://%{HTTP_HOST}/$1 [R=302,L]

################################################################
# BEGIN rlrssslReallySimpleSSL rsssl_version[2.3.14]
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
</IfModule>
# END rlrssslReallySimpleSSL

wp-config.php

//Begin Really Simple SSL Load balancing fix
if (isset($_SERVER["HTTP_X_FORWARDED_PROTO"] ) && "https" == $_SERVER["HTTP_X_FORWARDED_PROTO"] ) {
$_SERVER["HTTPS"] = "on";
}
//END Really Simple SSL