FATA[0000] Error response from daemon: v1 ping attempt failed with error: Get https://3xxxxxxxxxx.m.daocloud.io/v1/_ping: dial tcp 106.75.48.223:443: connection refused. If this private registry supports only HTTP or HTTPS with an unknown CA certificate, please add `--insecure-registry 3xxxxxxxxxx.m.daocloud.io` to the daemon's arguments. In the case of HTTPS, if you have access to the registry's CA certificate, no need for the flag; simply place the CA certificate at /var/packages/Docker/etc/certs/3xxxxxxxxxx.m.daocloud.io/ca.crt