error when add node

[JohanOu]

Short summary about the issue/question:
When I try to add a node through dev-box paictl,an error always occour:
UNREACHABLE! => {
"changed": false,
"msg": "Failed to connect to the host via ssh: Control socket connect(/root/.ansible/cp/ff32cdddd7): Connection refused\r\nFailed to connect to new control master\r\n",
"unreachable": true
}
I have delete the ~.ssh/known_host,but it doesn't work.
How to solve it?

OpenPAI Environment:

• OpenPAI version:v1.8.0
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Hardware (e.g. core number, memory size, storage size, GPU type etc.):
• Others:

Anything else we need to know: