have probleam in ssl lets script

[vahidalvandi]

hi please see my conf

Main mail domain

DOMAIN=my.domain.com

Hostnames for this server, separated with comas

HOSTNAMES=mail.domain.com

also i create /mailu/overrides/nginx/default.conf so added A record to static ip mail server for my and host sub domain . but not work and not open http or https

server {
  listen 443;
  server_name my.mailerchi.com;

  # [...] here goes your standard configuration

  location / {
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_pass https://localhost:8443;
  }
}

my docker logs :
Hint: The Certificate Authority failed to download the challenge files from the temporary standalone webserver started by Certbot on port 8008. Ensure that the listed domains point to this machine and that it can accept inbound connections from the internet