No certificate after changing domain name

My domain is:

I ran this command: sudo certbot certonly -a webroot --webroot-path=/usr/share/nginx/html --rsa-key-size 4096 -d

It produced this output:

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Starting new HTTPS connection (1):
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for
Using the webroot path /usr/share/nginx/html for all unmatched domains.
Waiting for verification...
Cleaning up challenges
Failed authorization procedure. (http-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Could not connect to

 - The following errors were reported by the server:

   Type:   connection
   Detail: Could not connect to

   To fix these errors, please make sure that your domain name was
   entered correctly and the DNS A record(s) for that domain
   contain(s) the right IP address. Additionally, please check that
   your computer has a publicly routable IP address and that no
   firewalls are preventing the server from communicating with the
   client. If you're using the webroot plugin, you should also verify
   that you are serving files from the webroot path you provided.

My operating system is (include version):
Linux CentOS-7.3

My web server is (include version):

I had request a Certificate in the past successfully, but after changing die domain name the certbot throws this error.

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