Почему проксирование статических файлов не работает?

2019/08/07 19:28:29 [error] 20488#20488: *19149 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: , request: "GET /example.com/static/robots.txt HTTP/1.0", upstream: "http://127.0.0.1:3000/example.com/static/robots.txt", host: "media-static"
2019/08/07 19:28:29 [error] 20488#20488: *19147 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: , request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:3000/favicon.ico", host: "example.com", referrer: "http://example.com/robots.txt"

map $sent_http_content_type $expires {
  "text/html" epoch;
  "text/html; charset=utf-8" epoch;
  default off;
}

upstream front {
  server 127.0.0.1:3000;
}

upstream media-static {
  server media.static;
}

server {
  listen 80 default_server;
  listen [::]:80 default_server;

  location / {
    rewrite ^/(.*)/$ /$1 permanent;
    expires $expires;
    proxy_pass http://front/;
    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;
  }

  location /robots.txt {
    proxy_pass http://media-static/$host/static/robots.txt;
    #proxy_pass http://media-static/$host/static$uri;
  }

  error_page 500 502 503 504 /custom_50x;

  location = /custom_50x {
    root /usr/share/nginx/html;
    default_type application/json;
    internal;
  }
}

proxy_pass http://127.0.0.1/$host/static$uri;
    proxy_set_header Host media.static;