Subdomain is not working Only show .html page but not running php files

I have a domain on bigrock and the hosting of the domain is on VPS using the CWP panel. Now I create a subdomain that's HTML pages are working fine but the .php files are not working and showing the error message

"Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later."

The domain is on CWP and it is working fine only the subdomain is showing this issue.

Don't get why this is not working fine.

try to rebuild your php installation and make sure you are running at least php 7.x or higher.

To change the port (default 80), open the apache / conf / httpd.conf file and find the line Listen 80 and ServerName localhost: 80 and replace port 80 with the port of your choice (for example 8080).
You can also probably change the ip address essay help online.

I have a domain on bigrock and the hosting of the domain is on VPS using the CWP panel. Now I create a subdomain that's HTML pages are working fine but the .php files are not working and showing the error message

"Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later."

The domain is on CWP and it is working fine only the subdomain is showing this issue.

Don't get why this is not working fine.

Check the error log /usr/local/apache/domlogs/your_domain_name.error.log