Subdomain sites accessible but not the main site?

I have a multisite setup on nginx/mysql.

It has run without a prob for some time.

I now noticed that I can access all sites on the subdomains incl. admin areas but NOT the main site / admin area.

The browser gives me a 101 (ERR_CONNECTION_RESET) when I try to access it.

– I resetted the server but to no avail

I dont know if it is handy since the site seemed to run for the past months fine but the nginx.conf (the link generated is this editor which transforms it in a http link so this is not in the file)

server
	{
        server_name			localhost deleau.eu  www.deleau.eu;
        root            	/opt/htdocs/html/;
		access_log      	/opt/nginx/var/log/deleaueu.access_log;
		error_log       	/opt/nginx/var/log/deleaueu.error_log;

		location ~ .php$ {
            fastcgi_read_timeout 120;
			fastcgi_pass   127.0.0.1:9000;
			fastcgi_index  index.php;
			#fastcgi_param  SCRIPT_FILENAME  /scripts/$fastcgi_script_name;
			fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
			include        fastcgi_params;
		}

		location = /robots.txt {
		    log_not_found off;
		    access_log off;
		}

		location /
		{
 			rewrite ^.*/files/(.*) /wp-includes/ms-files.php?file=$1;
			if (!-e $request_filename)
			{
				rewrite ^.+?/?(/wp-.*) $1 last;
				rewrite ^(.+)$ /index.php;
			}
}}

and the wp config bit:

define('WP_POST_REVISIONS', false);
define('WP_ALLOW_MULTISITE', true);
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', true );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'deleau.eu' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );
define( 'SUNRISE', 'on' );
define( 'FS_METHOD','direct');
define( 'NOBLOGREDIRECT', 'https://deleau.eu');