The problem has been resolved. I added the DNS name and the IP-Address of the Server to the host file of my PC. So I can reach my website from the outside and from my private LAN also.
WordPress rewrite multisite blog url
Can’t control WordPress Addresses from admin panel
Clear all rewrite_rules in the wp_options table in your database then open your local website in an incognito browser or clear your browser cache.
I believe that Multisite assumes that all sites are on the same server. That’s because it uses the same WP database for all of the sites. (Although the databases can get quite large if there are many sites, and lots of content. So you need to make sure the hosting server can handle large databases.) … Read more
If you know how WordPress is structured internally it should not be too hard. Here are the steps: For your site to migrate create a new site in the WordPress multisite environment (the information in the following tables must fit the new environment) wp_blogs (especially this) wp_blogs_versions (probably irrelevant) wp_registration_log (probably irrelevant) wp_signups (probably irrelevant) … Read more
disable site_url redirect in wp-login.php
Click on Dynamic on top right of link field for the button, select Site URL from the dropdown and you are good to go. The button link won’t change even when you change the site domain.
How to bulk edit image url in featured image and product description?
WordPress Multi-Site on Ubuntu 18.04 LAMP Keeps Re-Directing