Odtnhj

My goal is, to include on https://my-host.de/sub/include-to-show/ a page from a cms and manipulate it later via the subs_filter.
So i did a new location and made a proxy_pass to the page that i want to show and manipulate.
With the following config i get a status 502 on https://my-host.de/sub/include-to-show/ and a status 499 from https://my-host.de/sub/source-page - sadly no further logs

server 
 listen 443 ssl http2;
 listen [::]:443 ssl http2;

 server_name my-host.de;

 ssl_certificate /etc/nginx/ssl/bundle.pem;
 ssl_certificate_key /etc/nginx/ssl/key.pem;
 include snippets/ssl-parameters.conf;

 root /var/www/my-host/htdocs;
 index index.php;

 access_log /var/www/my-host/logs/access.log;
 error_log /var/www/my-host/logs/error.log;

 client_max_body_size 512M;

 location / 
 try_files $uri $uri/ /index.php?$args;
 

 location ~ /(.+.php)$ 
 try_files $uri =404;

 fastcgi_pass unix:/run/php/php7.1-fpm-default.sock;
 fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

 include fastcgi_params;

 fastcgi_buffers 16 16k;
 fastcgi_buffer_size 32k;

 include /etc/nginx/snippets/fastcgi-php.conf;
 

 location /sub/include-to-show/ 
 proxy_pass https://my-host.de/sub/source-page;
 proxy_redirect default;
 

If i change the Domain from the proxy_pass to another one it works.
What am i doing wrong?

Already tried this settings in the proxy_pass location part:

proxy_ignore_client_abort on;
proxy_set_header Host $host:$server_port;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Edit: By the way - the Setup worked 2 weeks ago. Currently on debian stretch