luceos Thank you for your quick reply. I tried to change accordingly in my apache server. But seems still when I browse with www it does not redirect to https://...
My htaccess file configured accordingly. And config.php also show this url: https://forum.assistavenue.com. Thank you for your kind help.
<IfModule mod_headers.c>
RequestHeader unset Proxy
</IfModule>
RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-SSL} !on
RewriteCond %{HTTP_HOST} ^forum\.assistavenue\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.forum\.assistavenue\.com$
RewriteRule ^/?$ "https\:\/\/forum\.assistavenue\.com\/" [R=301,L]