Get the client ip adress from servlet when tomcat is accessed via nginx-load balancer

I am using nginx as load balancer with a few tomcat servers as backends. Web-clients are java-scripts which from the website post a request to the Load-balancer.

So the path is following:

client-xhttp-request from PC1 having IP 1
via Javascript hosted on domainA.com (server A with IP 2)

Request is posted to --> backend.domainA.com (also on server A with IP 2)
Load balancer upstreams the request to --> Tomcat (on servers B, C or D)

When executing the servlet request directly to the Tomcat Server, I get the desired client IP 1, so I can exclude that the problem lies in programming errors.

I tried below configuration but still I am receiving back only the IP 2 of the web-server A instead of the desired IP 1 of the requesting client. How do I need to configure the nginx-part to retrieve IP 1?

nginx.conf:

user www-data;
    ---- other stuff
    
http {
    
    --- other stuff
    
    
    upstream backend {
        server mytomcat1.serverB.com  max_fails=1 fail_timeout=2s;
        server mytomcat2.serverC.com  max_fails=2 fail_timeout=5s;
        server mytomcat3.serverD.com  max_fails=2 fail_timeout=5s;
    }
}

sites-available/com.domainA.backend

server {
       listen         80;
       server_name    backend.domainA.com;
       # Redirect all traffic to SSL:
       rewrite ^ https://$server_name$request_uri? permanent; 
       set_real_ip_from unix:;
       real_ip_header X-Real-IP;
       real_ip_recursive on;
}
 
server {
    listen 443 ssl;
    server_name     backend.domainA.com;
    ...
    other stuff
    ...
    location / {
            proxy_set_header  Host $host;
            proxy_set_header  X-Real-IP $remote_addr;
            proxy_set_header  X-Forwarded-Proto https;
            proxy_set_header  X-Forwarded-For $remote_addr;
            proxy_set_header  X-Forwarded-Host $remote_addr;
            proxy_pass http://backend;
        }
    }

sites-available/com.domainA

server {
       listen         80;
       server_name    domainA.com www.domainA.com;
       # Redirect all traffic to SSL
       rewrite ^ https://$server_name$request_uri? permanent; 
}
server {
    listen 443 ssl;
    server_name    domainA.com www.domainA.com;
   
    location  / {
        root /var/www/html/ ... ;
   }
}