reverse proxy for multiple server nginx

nginx.conf

upstream preprod-apim-am.wavemoney.io {
    server localhost:3000;
}
upstream preprod-apim-gw.wavemoney.io {
    server localhost:4000;
}

server {
    listen 80;
    server_name preprod-apim-am.wavemoney.io;

    location / {
        proxy_pass http://preprod-apim-am.wavemoney.io;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }

}


server {
    listen 80;
    server_name preprod-apim-gw.wavemoney.io;

    location / {
        proxy_pass http://preprod-apim-gw.wavemoney.io;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }

}