Multisite index.php not Redirecting

Hello,

I have a strange problem with my multisite setup:
https://applebun.com – My original page works 100%
https://sg.multisite.com – My new multisite does not open the index.php but shows the standard Apache error instead. However, all subpages (like posts, admin dashboard etc) are working perfectly fine.

I have done pretty much everything as required for multisites to work:
– DNS Wildcard is configured, working (*.applebun.com) and pointin at the public html folder where wordpress is installed
– wp-config, htaccess are configured as required
– Blog Directory has been created in wp-content

Again, I can access https://sg.applebun.com/wp-admin and every single page on that site as well, for example https://sg.applebun.com/2012/05/09/test/

Even if i call https://sg.applebun.com/index.php directly -> goes to https://sg.applebun.com -> goes to https://sg.applebun.com/cgi-sys/defaultwebpage.cgi

This is my htaccess code:

#Made Multi-Site with Multi-Site Enabler 1.5#
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
</IfModule>

## EXPIRES CACHING ##
<IfModule mod_expires.c>
ExpiresActive On
ExpiresByType image/jpg "access 1 year"
ExpiresByType image/jpeg "access 1 year"
ExpiresByType image/gif "access 1 year"
ExpiresByType image/png "access 1 year"
ExpiresByType text/css "access 1 month"
ExpiresByType application/pdf "access 1 month"
ExpiresByType text/x-javascript "access 1 month"
ExpiresByType application/x-shockwave-flash "access 1 month"
ExpiresByType image/x-icon "access 1 year"
ExpiresDefault "access 2 days"
</IfModule>
## EXPIRES CACHING ##

This is my wp-config code:

define (‘WP_ALLOW_MULTISITE’, true);
define ('MULTISITE', '1');
define ('SUBDOMAIN_INSTALL', '1');
define ('DOMAIN_CURRENT_SITE', 'applebun.com');
define ('PATH_CURRENT_SITE', '/');
define ('SITE_ID_CURRENT_SITE', 1);
define ('BLOG_ID_CURRENT_SITE', 1);
$base = '/';