When updating wordpress, this error appears:
Error message: cURL error 28: Connection timed out after 10001 milliseconds
Resolution: Curl the site with the private IP and not the public IP. From inside the private network each server or device is known only by it’s private IP address and is always referenced using that address.
Ref: https://www.the-art-of-web.com/system/iptables-nat/
Also, on cpanel that is behind a firewall, you can check the file for the mappings:/var/cpanel/cpnat