TLS failed in Docker

I have very limited knowledge about TLS certification. I wanted to enable https for docker daemon. I followed this tutorial but at the end failed to start docker daemon.

I am using docker in a Ubuntu 16.04 VM and my client and server is the same machine. So I use the $hostname as the 'Common Name' during all the process.

After following the whole process in docker documentation when I run

sudo dockerd --tlsverify --tlscacert=ca.pem --tlscert=server-cert.pem --tlskey=server-key.pem -H=0.0.0.0:2376

I get the INFO log that "API listen on [::]:2376"

When I use the below command:

docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=$HOST:2376 version

I get proper response.

But when I reload the daemon and try to start docker it says failed to start docker and give the following message-

Job for docker.service failed because the control process exited with error code.  
See "systemctl status docker.service" and "journalctl -xe" for details.

Output of 'journalctl -xe' is:

I copied the necessary certificate to ~/.docker/ and the 'ExecStart' in my /lib/systemd/system/docker.service file is:

ExecStart=/usr/bin/dockerd -H fd:// -H 0.0.0.0:2376 \
     --tlsverify --tlscacert=/home/sakib/.docker/ca.pem \
     --tlskey=/home/sakib/.docker/key.pem \
     --tlscert=/home/sakib/.docker/cert.pem

When I try to communicate with the API I get the following response:

$ curl -X GET https://0.0.0.0:2376/images/json

curl: (35) gnutls_handshake() failed: Certificate is bad

$ docker version

Client:
 Version:      1.12.1
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   23cf638
 Built:        Thu Aug 18 05:33:38 2016
 OS/Arch:      linux/amd64
An error occurred trying to connect: Get https://EL802:2376/v1.24/version: x509: certificate is valid for $HOST, not EL802 

NOTE: EL802 is my hostname which I set as the 'HOST' environment variable.

I think the problem is with the 'CN' name that I chose while creating client certificate. I create the server and client certificate as below-

Server:

openssl req -subj "/CN=$HOST" -sha256 -new -key server-key.pem -out server.csr               

Client:

openssl req -subj '/CN=$HOST' -new -key key.pem -out client.csr

As my client and server is my host machine(EL802) which I set as the $HOST variable.