thanks for your answer @lzap
I think below topic make the issue:
and when I type:
# hammer host list --search ‘last_report < “35 minutes ago” and status.enabled = true’
SSL certificate verification failed
Make sure you configured the correct URL and have the server’s CA certificate installed on your system.
The following configuration option were used for the SSL connection:
ssl_ca_file = /etc/letsencrypt/live/foreman.local/chain.pem
Make sure the location contains an unexpired and valid CA certificate for https://foreman.local.