Elasticsearch can't execute watcher due to hooks.slack not being resolved

I Have elasticsearch v7.9.1
Kibana v7.9.1
unfortunately the watchers have stopped working after I set up x-pack security.
I cannot curl hooks.slack.com , this is my result.

curl -v https://hooks.slack.com

* Could not resolve host: hooks.slack.com
* Closing connection 0
curl: (6) Could not resolve host: hooks.slack.com

I have added a new Webhooks to elasticsearch keystore and the elasticsearch.yml file looks like this.

xpack.security.enabled: true
xpack.security.transport.ssl.enabled: true
xpack.http.ssl.verification_mode: none

xpack.watcher.enabled: true
xpack.notification.slack:
  account:
    monitoring:
       message_defaults.from: Kibana
       message_defaults.icon: true

and the keystone url is : xpack.notification.slack.account.monitoring.secure_url

Theses are the errors I get in elasticsearch.log is:

[ERROR][o.e.x.w.n.s.SlackService ] [node-1] failed to execute slack api http request
ERROR][o.e.x.w.n.s.SlackService ] [node-1] failed to execute slack api http request

can anyone help me with this issue.

Tried this on my laptop;

~ curl -v https://hooks.slack.com
*   Trying 52.63.104.105...
* TCP_NODELAY set
* Connected to hooks.slack.com (52.63.104.105) port 443 (#0)

Sounds like you may have a DNS issue in your network, rather than an Elasticsearch issue.

yes it was a DNS problem. thank you