Wordpress Multisite hinter NGINX Proxy Manager

server {
	listen 80;
	server_name domain.tld sub1.domain.tld sub2.domain.tld;
	location / {		
		proxy_set_header Host $host;
		proxy_set_header X-Forwarded-Proto $scheme;
		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
		proxy_set_header X-Real-IP $remote_addr;
		proxy_set_header Upgrade $http_upgrade;
		proxy_set_header Connection "Upgrade";  
		proxy_pass http://192.168.1.20:80;
	}
}

<VirtualHost *:80>
        ServerName domain.tld
        ServerAlias *.domain.tld
        DocumentRoot /usr/share/wordpress/
        DirectoryIndex index.php index.html
        ErrorLog /var/log/apache2/wp-error.log
        TransferLog /var/log/apache2/wp-access.log

        <Directory /usr/share/wordpress>
            AllowOverride All
            Options FollowSymLinks
            Require all granted
        </Directory>
</VirtualHost>

// ...
define('WP_ALLOW_MULTISITE',true);  
define('MULTISITE',true);  
define('SUBDOMAIN_INSTALL', true );  
define('DOMAIN_CURRENT_SITE', 'domain.tld' );  
define('PATH_CURRENT_SITE', '/' );  
define('SITE_ID_CURRENT_SITE', 1 );  
define('BLOG_ID_CURRENT_SITE', 1 );  
// ....

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

</IfModule>