I can't regiter SSL

Hi
I registered a new User account and installed the WordPress website, Now I want to add SSL for that but unfortunately, I got an Error:

Code: [Select]

- mydomain.com
Error Message:
[Thu Sep 22 09:47:57 +0330 2022] Using CA: https://acme-v02.api.letsencrypt.org/directory
[Thu Sep 22 09:47:57 +0330 2022] Multi domain='DNS:www.mydomain.com,DNS:mydomain.com'
[Thu Sep 22 09:47:57 +0330 2022] Getting domain auth token for each domain
[Thu Sep 22 09:48:00 +0330 2022] Getting webroot for domain='www.mydomain.com'
[Thu Sep 22 09:48:00 +0330 2022] Getting webroot for domain='mydomain.com'
[Thu Sep 22 09:48:00 +0330 2022] Verifying: www.mydomain.com
[Thu Sep 22 09:48:01 +0330 2022] Pending, The CA is processing your order, please just wait. (1/30)
[Thu Sep 22 09:48:03 +0330 2022] www.mydomain.com:Verify error:x.x.x.x: Fetching https://mydomain.com/.well-known/acme-challenge/<some key>: Connection refused
[Thu Sep 22 09:48:03 +0330 2022] Please check log file for more details: /root/.acme.sh/acme.sh.log

I have other websites and domains on this server, for that, I don't have a problem
how can track the problem and fix that?