Nginx reverse proxy to another nginx loop

Hi there, I want to install Prestashop on a dedicated Nginx server called “presta” (192.168.1.19). Not used to nginx and I wonder why I get redirection cycle, would need your advice.

On my front end nginx let’s call it “rproxy” 192.168.1.5 I have this configuration :

server {
    if ($host = www.mydomain.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot
        listen   80;
        server_name     www.mydomain.com;
                return 301 https://www.mydomain.com$request_uri;
}
server {
    listen 443;
    server_name www.mydomain.com;
    error_log /var/log/nginx/mydomain.error.log;
    access_log /var/log/nginx/mydomain.access.log;

    ssl on;
    ssl_certificate /etc/letsencrypt/live/www.mydomain.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/www.mydomain.com/privkey.pem; # managed by Certbot
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    set $upstream 192.168.1.19;
    location / {
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_pass_header Authorization;
        proxy_pass http://$upstream;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_buffering off;
        client_max_body_size 0;
        proxy_read_timeout 36000s;
        proxy_redirect off;
    }
}

and on my dedicated nginx server I get this :

server {
        listen   80;
        server_name     www.mydomain.com;

        root /var/www/mydomain;
                index index.php index.html index.htm;

                if ($http_host != "www.mydomain.com") {
                rewrite ^ https://www.mydomain.com$request_uri permanent;
                }
                location = /favicon.ico {
                log_not_found off;
                access_log off;
                }
                location = /robots.txt {
                allow all;
                log_not_found off;
                access_log off;
                }
                # deny access to .htaccess files, if Apache's document root
                # concurs with nginx's one
                location ~ /\. {
                deny all;
                access_log off;
                log_not_found off;
                }
                location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ /index.html;
                #try_files $uri $uri/ =404;
                # Uncomment to enable naxsi on this location
                # include /etc/nginx/naxsi.rules
                }

                rewrite ^/api/?(.*)$ /webservice/dispatcher.php?url=$1 last;
                rewrite ^/([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$1$2$3.jpg last;
                rewrite ^/([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$1$2$3$4.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$1$2$3$4$5.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$1$2$3$4$5$6.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$1$2$3$4$5$6$7.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$1$2$3$4$5$6$7$8.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$1$2$3$4$5$6$7$8$9.jpg last;
                rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$8/$1$2$3$4$5$6$7$8$9$10.jpg last;
                rewrite ^/c/([0-9]+)(\-[\.*_a-zA-Z0-9-]*)(-[0-9]+)?/.+\.jpg$ /img/c/$1$2$3.jpg last;
                rewrite ^/c/([a-zA-Z_-]+)(-[0-9]+)?/.+\.jpg$ /img/c/$1$2.jpg last;
                rewrite ^/images_ie/?([^/]+)\.(jpe?g|png|gif)$ /js/jquery/plugins/fancybox/images/$1.$2 last;

                try_files $uri $uri/ /index.php$is_args$args;
                error_page 404 /index.php?controller=404;

                location ~* \.(gif)$ {
                expires 2592000s;
                }
                location ~* \.(jpeg|jpg)$ {
                expires 2592000s;
                }
                location ~* \.(png)$ {
                expires 2592000s;
                }
                location ~* \.(css)$ {
                expires 604800s;
                }
                location ~* \.(js|jsonp)$ {
                expires 604800s;
                }
                location ~* \.(js)$ {
                expires 604800s;
                }
                location ~* \.(ico)$ {
                expires 31536000s;
                }

                # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
                #
                location ~ \.php$ {
                        include snippets/fastcgi-php.conf;
                #fastcgi_pass 127.0.0.1:9000;
                #fastcgi_index  index.php;
                        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
                        fastcgi_pass unix:/var/run/php/php7.3-fpm.sock;
                }
}

I always got the following error :

2019/12/22 15:44:56 [error] 3031#3031: *9 open() "/var/www/mydomain/img/app_icon.png" failed (2: No such file or directory), client: 192.168.1.5, server: www.mydomain.com, request: "GET /img/app_icon.png HTTP/1.1", host: "www.mydomain.com"
2019/12/22 15:45:03 [error] 3031#3031: *82 open() "/var/www/mydomain/img/app_icon.png" failed (2: No such file or directory), client: 192.168.1.5, server: www.mydomain.com, request: "GET /img/app_icon.png HTTP/1.1", host: "www.mydomain.com"

Would appreciate your help on this guys!