mmmmh...
So, wieder etwas Zeit für Contao 
Die Installation in einen Docker-Container klappt reibungslos.
Was mich aktuell noch etwas stört: eine 0815-Site anzulegen klappt tadellos, die offizielle Contao-Demo zu installieren hingegen gar nicht.
Ich habe es auch schon mittels dem Contao Manager (phar) probiert. Das klappt bis zu dem Punkt an dem das Frontend nur per /app.php/ aufrufbar ist.
Daher gehe ich mal davon aus, das es an der .htaccess liegt. (habe hierzu im Forum ja schon zig Einträge gefunden...)
Im web-Ordner liegt folgende Datei, kann jemand bitte validieren ob das eine "originale" oder durch den Manager bereits modifizierte Datei ist?
Danke
	Code:
	<IfModule mod_rewrite.c>
    RewriteEngine On
    <IfModule mod_headers.c>
        # Assets in /assets and /bundles either contain a hash in their filename
        # or are called with a ?version suffix, therefore cache them for 1 year.
        RewriteRule ^(assets|bundles)/ - [ENV=CONTAO_ASSETS:true]
        Header set Cache-Control "max-age=31536000" env=CONTAO_ASSETS
        # Allow CORS on the Contao TinyMCE skin.
        RewriteRule ^assets/tinymce4/js/skins/contao/fonts/ - [ENV=CONTAO_TINYMCE_SKIN:true]
        Header set Access-Control-Allow-Origin "*" env=CONTAO_TINYMCE_SKIN
    </IfModule>
    # Determine the RewriteBase automatically and set it as environment variable.
    # If you are using Apache aliases to do mass virtual hosting or installed the
    # project in a subdirectory, the base path will be prepended to allow proper
    # resolution of the index.php file and to redirect to the correct URI. It will
    # work in environments without path prefix as well, providing a safe, one-size
    # fits all solution. But as you do not need it in this case, you can comment
    # the following 2 lines to eliminate the overhead.
    RewriteCond %{REQUEST_URI}::$1 ^(/.+)/(.*)::\2$
    RewriteRule ^(.*) - [E=BASE:%1]
    # Sets the HTTP_AUTHORIZATION header removed by Apache
    RewriteCond %{HTTP:Authorization} .
    RewriteRule ^ - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
    # Redirect to URI without front controller to prevent duplicate content
    # (with and without `/index.php`). Only do this redirect on the initial
    # rewrite by Apache and not on subsequent cycles. Otherwise we would get an
    # endless redirect loop (request -> rewrite to front controller ->
    # redirect -> request -> ...).
    # So in case you get a "too many redirects" error or you always get redirected
    # to the start page because your Apache does not expose the REDIRECT_STATUS
    # environment variable, you have 2 choices:
    # - disable this feature by commenting the following 2 lines or
    # - use Apache >= 2.3.9 and replace all L flags by END flags and remove the
    #   following RewriteCond (best solution)
    RewriteCond %{ENV:REDIRECT_STATUS} ^$
    RewriteRule ^index\.php(?:/(.*)|$) %{ENV:BASE}/$1 [R=301,L]
    # If the requested filename exists, simply serve it.
    # We only want to let Apache serve files and not directories.
    RewriteCond %{REQUEST_FILENAME} -f
    RewriteRule ^ - [L]
    # Rewrite all other queries to the front controller.
    RewriteRule ^ %{ENV:BASE}/index.php [L]
</IfModule>
<IfModule !mod_rewrite.c>
    <IfModule mod_alias.c>
        # When mod_rewrite is not available, we instruct a temporary redirect of
        # the start page to the front controller explicitly so that the website
        # and the generated links can still be used.
        RedirectMatch 302 ^/$ /index.php/
        # RedirectTemp cannot be used instead
    </IfModule>
</IfModule>