In what way does Site1.subdomain.com not work?
Home page does not load
What is the result of that request?
I get the error:
“Forbidden
You don’t have permission to access /index.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.”
The theme’s nothing found (404.php) template?
No I don’t get the themes 404 page.
What is set for homepage display in Reading Settings of that site?
Do other similar sub-sites work, or the same result?
All sub-domain sites give the same issue. The main domain does not.