title: my docker cannot use private registry(503 Service Unavailable)
body: <p>I want to deploy my code to the environment of production.But when I trying to run this command: </p>
  
  <pre><code>  docker login -u admin -p admin123 172.xxx.x.xxx:30003
  </code></pre>
  
  <p>it returned me "503 service unavailable". 
  it told me "connection refused" when I <code>curl http://172.xxx.x.xxx:30003</code> ,</p>
  
  <p>it's not the first time I deploy this code and this phenomenon has never arise untill last week ,how can I do with this strange problem??</p>
  
  <p>1.restart docker service
  2.upgrade docker desktop(with Mac system)
  but still the same!</p>
  
  <p>my daemon.json :</p>
  
  <pre><code>{
    "insecure-registries" : [
      "172.xxx.xxx.xxx:30003",
      "127.0.0.1:5000"
    ]
  }
  </code></pre>
  
  <p>and this is the context:</p>
  
  <pre><code>Yutongs-MacBook-Pro-2:~ yutong.liu$ docker login -u admin -p admin123 172.xxx.xxx.xxx:30003
  WARNING! Using --password via the CLI is insecure. Use --password-stdin.
  Error response from daemon: login attempt to http://172.xxx.xxx.xxx:30003/v2/ failed with status: 503 Service Unavailable
  
  Yutongs-MacBook-Pro-2:~ yutong.liu$ curl http://172.xxx.xxx.xxx:30003/
  curl: (7) Failed to connect to 172.xxx.xxx.xxx port 30003: Connection refused
  </code></pre>