I want to send a request between two clusters using nginx on a separate server
there is an nginx server to route via upstream to two identical backends in two different clusters
, let’s say the validator application is deployed in two clusters and has different ingress addresses
validator.amd.com
validator.bm.com

I set it up on nginx like this

server {
    listen 80;
    server_name test.test.com;
    location / {
            return 301 https://$host$request_uri;
               }
}
upstream valid{
server validator.amd.com:80;
server  validator.bm.com:80;
}
server {
    listen 443 ssl;
    server_name test.test.com;
     ssl_certificate test.test.com.crt;
     ssl_certificate_key test.test.com.key;



    location / {
     return 204;
    }

    location /keepalive {
       return 200;
               }
    location /api/valid {
        proxy_set_header Content-Type application/json;
        proxy_pass http://valid/api/validators;

    }
}

it doesn’t work at all through the upstream
, but if I proxy

location /api/valid {
        proxy_set_header Content-Type application/json;
        proxy_pass http://validator.amd.com/api/validators;

    }

then everything is OK, similarly, if you put another domain
, I do not understand what the catch might be and why everything works directly, and if there is no upstream, please tell me?
I also tried adding headers

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_set_header X-Forwarded-Proto $scheme; proxy_set_header
Content-Type application/json;