Redirect loop for WWW WordPress Multisite – possible htaccess issue?

The network area of my multisite isn’t working – it creates a redirect loop when I go to: http://www.mysite.com/wp-admin/network

I wanted to remove WWW from the Domain_current_site in wp-config to fix the issue, BUT when I do that, something weird happens: all the internal pages redirect to the homepage. For example: mydomain.com/about redirects to the homepage. Interestingly enough, posts work fine, but pages redirect to the homepage.

I tried re-saving the permalink structure which is set to /postname/ but it didn’t help.

In my wp-config.php it says:
define('DOMAIN_CURRENT_SITE', 'www.mydomain.com');

In my htaccess I set up a redirect from non-www urls to www urls. Here’s what the htaccess looks like

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [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]