Problem with redirect to subfolder Error 404 Index.php not found

Hello Community,
I use the following configurations The Perfect Server - Debian 9 (Nginx, BIND, Dovecot, ISPConfig 3.1)
Debian and Nginx is working fine with the default settings.
The index.html with the NGINX default path (/var/www/clients/client1/web1) is also working.
Now i have the Problem to change the path of the index.html to another directory (/var/www/clients/client1/web1/subfolder) with ISPConfig.
When I redirect with "permanent" there is an 404 error not found
How can I modify the vhost to make the index.php run?
Please can anybody help me? I am digging around since days, also I found nothing in the manual, which is understanable for newbies

Thank you for your efforts (I am a beginner)
snicker

vhost.conf

Code:

server {
        listen IP4:80;

        listen Ip4:443 ssl http2;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_certificate /var/www/clients/client1/web1/ssl/mydomain-le.crt;
        ssl_certificate_key /var/www/clients/client1/web1/ssl/mydomain-le.key;

        server_name mydomain ;

        root   /var/www/mydomain/web/;

        if ($http_host = "www.mydomain-path.de") {
            rewrite ^ $scheme://mydomain$request_uri? permanent;
        }
        if ($scheme != "https") {
            rewrite ^ https://$http_host$request_uri? permanent;
        }

        rewrite ^(?!/(subfolder|stats|error|\.well-known/acme-challenge))/(.*)$ /subfolder/$2 permanent;
        index index.html index.htm index.php index.cgi index.pl index.xhtml;



        error_page 400 /error/400.html;
        error_page 401 /error/401.html;
        error_page 403 /error/403.html;
        error_page 404 /error/404.html;
        error_page 405 /error/405.html;
        error_page 500 /error/500.html;
        error_page 502 /error/502.html;
        error_page 503 /error/503.html;
        recursive_error_pages on;
        location = /error/400.html {

            internal;
        }
        location = /error/401.html {

            internal;
        }
        location = /error/403.html {

            internal;
        }
        location = /error/404.html {

            internal;
        }
        location = /error/405.html {

            internal;
        }
        location = /error/500.html {

            internal;
        }
        location = /error/502.html {

            internal;
        }
        location = /error/503.html {

            internal;
        }

        error_log /var/log/ispconfig/httpd/mydomain-path.de/error.log;
        access_log /var/log/ispconfig/httpd/mydomain-path.de/access.log combined;

        location ~ /\. {
            deny all;
        }

        location ^~ /.well-known/acme-challenge/ {
            access_log off;
            log_not_found off;
            root /usr/local/ispconfig/interface/acme/;
            autoindex off;
            index index.html;
            try_files $uri $uri/ =404;
        }

        location = /favicon.ico {
            log_not_found off;
            access_log off;
            expires max;
            add_header Cache-Control "public, must-revalidate, proxy-revalidate";
        }

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

        location /stats/ {

            index index.html index.php;
            auth_basic "Members Only";
            auth_basic_user_file /var/www/clients/client1/web1/web/stats/.htpasswd_stats;
        }

        location ^~ /awstats-icon {
            alias /usr/share/awstats/icon;
        }

        location ~ \.php$ {
            try_files /69ac73998d9ca71910a6a11fefc4ce52.htm @php;
        }

        location @php {
            try_files $uri =404;
            include /etc/nginx/fastcgi_params;
            fastcgi_pass unix:/var/lib/php7.0-fpm/web1.sock;
            fastcgi_index index.php;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_intercept_errors on;
        }




        location / {
            index index.php;
            try_files $uri $uri/ /index.php?$query_string;
        }

        location /public/ {
            sendfile                                    on;
            tcp_nopush                              on;
            tcp_nodelay                              on;
            keepalive_timeout                   10s;
            sendfile_max_chunk              512k;
        }



}