Wordpress installation in subfolder backend not accessable - wordpress

Question

I have a Wordpress installation in the root folder of my server and another Wordpress installation in a subfolder called "neueseite".
I can access the frontend of the page in the subfolder but not the admin area (backend). When I try to access it, it shows me a 404 error: https://paarkultur.ch/neueseite/wp-login.php
All URLs in the database contain the URL with the subfolder. I also tried different things with the .htaccess file. Nothing helped.
Here is the code inside the root directory's .htaccess file:
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
# Include in the next line all folders to exclude
RewriteCond %{REQUEST_URI} !(neueseite) [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
And this is the code in the subfolders .htaccess file:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /neueseite/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /neueseite/index.php [L]
</IfModule>
Can someone help me figure out what the problem could be?

Answer 1

I checked your nginx server and the below file is not located in the directory listed below:
https://paarkultur.ch/neueseite/wp-login.php
I can see that you have various core files such as wp-config.php, readme.html, etc but you do not have wp-login.php in that directory.
Anyway if you are trying to serve multiple sites from a single server then you are going the wrong way about it