Error response from: get https://20.0.0.100/v2/ : dial tcp 20.0.0.100:443: connect: connection refused

The reason for this problem is that the docker registry uses HTTPS by default, but the private mirror is built
like HTTP service by default, so the following error occurs when interacting with the private mirror.

Solution:
you must first specify the address of the private warehouse — insure registry

[root@client ~]# vim /usr/lib/systemd/system/docker.service

ExecStart=/usr/bin/dockerd -H fd:// --insecure-registry 20.0.0.10 --containerd=/run/containerd/containerd.sock

[root@client ~]# systemctl daemon-reload 
[root@client ~]# systemctl restart docker

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