503 error from curl Request to site api under Cloudflare

I am getting 503 error when I try to use curl Request to api of my site.
Plesk is installed on the server and I set the scheduled tasks to do the curl Request to this site’s api endpoint. But I am getting error after run the task.
503 error.
I am now thinking two way to solve.

  1. the api request from this site’s ip address (the curl request comes from this site itself, I think) should be whiltelisted.
  2. the api request from anywhere might be bypass the Clouldfare.

But I can’t find any detailed solution.
Anyone can help me?
Best Regards.