Register an already existing Docker Engine to Docker Machine

I have Docker Engine installed on an Ubuntu 14.04 LTS server. Recently I installed Docker Machine on another Ubuntu 14.04 LTS server. I am trying to register the already existing Docker Engine to the Docker Machine.

I used the following command for the same

docker-machine create --driver none --url=tcp://xx.xx.xx.xx:xxxx default

But I am getting the below error

Unable to query docker version: Get https://xx.xx.xx.xx:xxxx/v1.15/version: http: server gave HTTP response to HTTPS client

I am doing it all with the root user.

when I tried to execute the below command, I got the error of timeout

docker-machine regenerate-certs default

Regenerate TLS machine certs? Warning: this is irreversible. (y/n): y
Regenerating TLS certificates
Waiting for SSH to be available…
Too many retries waiting for SSH to be available. Last error: Maximum number of retries (60) exceeded

I am unable to execute the below command as well.

root@instance-1:~# docker-machine ssh default
usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]
** [-D [bind_address:]port] [-E log_file] [-e escape_char]**
** [-F configfile] [-I pkcs11] [-i identity_file]**
** [-L [bind_address:]port:host:hostport] [-l login_name] [-m mac_spec]**
** [-O ctl_cmd] [-o option] [-p port]**
** [-Q cipher | cipher-auth | mac | kex | key]**
** [-R [bind_address:]port:host:hostport] [-S ctl_path] [-W host:port]**
** [-w local_tun[:remote_tun]] [user@]hostname [command]**
exit status 255

Can somebody please help me with this.