Error: nginx as reverse proxy for Apache

Hello everbody,

I have a working Nextcloud running on my local Apache which I want to access through a domain, I setup in ISPConfig which is running on nginx.
But all I get is a 500 Internal Server Error from nginx.

Apache is running on port 8082, configured in /etc/apache2/ports.conf

Code:

Listen 8082

#<IfModule ssl_module>
#       Listen 443
#</IfModule>

#<IfModule mod_gnutls.c>
#       Listen 443
#</IfModule>

Confirmed by netstat:

Code:

tcp6       0      0 :::8082                 :::*                    LISTEN      15340/apache2

Apache's only enabled site:

Code:

<VirtualHost 127.0.0.1:8082>
        ServerAdmin     webmaster@localhost
        DocumentRoot    /var/www/html/nextcloud

        ErrorLog        ${APACHE_LOG_DIR}/nextcloud_error.log
        CustomLog       ${APACHE_LOG_DIR}/nextcloud_access.log combined

#        <Directory /var/www/http/nextcloud/>
#                Options         -Indexes +FollowSymlinks
#                AllowOverride   All
#                <IfModule mod_dav.c>
#                                Dav off
#                </IfModule>
#                SetEnv          HOME /var/www/http/nextcloud
#                SetEnv          HTTP_HOME /var/www/http/nextcloud
#                Satisfy         Any
#        </Directory>
# this is commented out because I dunno if that breaks things
        <Directory /var/opt/nextcloud-data/>
                Require         all denied
        </Directory>
</VirtualHost>

nginx vhost file from ISPConfig (modified by me):

Code:

server {
        listen *:80;
        listen *:443 ssl;
                ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_certificate /var/www/clients/client1/web5/ssl/...
        ssl_certificate_key /var/www/clients/client1/web5/ssl/...

        server_name subdomain.domain.tld;

        root    /var/www/html/nextcloud;
        #root   /var/www/subdomain.domain.tld/web/;
        # this was the original ISPConfig root path

        index index.html index.htm index.php index.cgi index.pl index.xhtml;

        location / {
            proxy_pass http://localhost:8082;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
            proxy_set_header X-Forwarded-Proto $scheme;
        }

        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/subdomain.domain.tld/...
        access_log /var/log/ispconfig/httpd/subdomain.domain.tld/...

        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/web5/web/...
        }

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

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


        location @php {
            deny all;
        }

}

Maybe I'm missing some settings for the domain inside of ISPConfig?
I followed a lot of setups on how to reverse proxy from nginx to Apache by now but I still can't figure out why this is not happening.

Edit: If I set PHP in ISPConfig to PHP-FPM, I get a 404 error "The requested URL was not found on this server.". Before it was deactivated.

I am grateful for any help. Thank you!

 

I'm getting 403s now...so something changed.
Error.log

Code:

2018/09/11 20:38:28 [error] 18084#18084: *2363 access forbidden by rule, client: ip.ip.ip.ip, server: subdomain.domain.tld, request: "GET /status.php HTTP/1.1", host: "subdomain.domain.tld"

Access.log

Code:

ip.ip.ip.ip - name [11/Sep/2018:20:40:36 +0200] "GET /status.php HTTP/1.1" 403 872 "-" "Mozilla/5.0 (Macintosh) mirall/2.3.3 (build 84) (Nextcloud)"