docker pull 命令超时 ，timeout 或者拒绝服务 connection refused

修改docker配置文件
mkdir -p /etc/docker/daemon.json
vi /etc/docker/daemon.json

将下边配置信息写入该文件

{
"builder": {
    "gc": {
      "defaultKeepStorage": "20GB",
      "enabled": true
    }
  },
  "experimental": false,
  "registry-mirrors": [
    "https://docker.m.daocloud.io",
    "https://docker.imgdb.de",
    "https://docker-0.unsee.tech",
    "https://docker.hlmirror.com",
    "https://docker.1ms.run",
    "https://func.ink",
    "https://lispy.org",
    "https://docker.xiaogenban1993.com"
  ]
}

重启docker

systemctl daemon-reload
systemctl restart docker