Error in redirecting request?

Greetings,

I’m running WP on my Synology NAS using the “official” package from Synology. It works great, but today i tried to enable Network Sites using http://codex.ww.wp.xz.cn/Create_A_Network as my tutorial.

After having completed step 4, i.e. inserting this:

define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'MYDOMAIN.COM:443');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

into the /wordpress/wp-config.php, and this:

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).*) wordpress/$2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ wordpress/$2 [L]
RewriteRule . index.php [L]

into the root .htaccess file i get a redirect error in Firefox.

“
The Page isen’t rendering properly.

Firefox has detected that the server is redirecting the request for this address in a way that will never complete.
“

I have tried to clear cookies etc, but to no avail.
After a bit of troubleshooting it seems that it is the additions to the wp-config.php that makes the server crash (i.e. not even the primary one is working) If I only edit .htaccess file, at least the primary site is fine.

Any hits?