How to setup Subdomain to be working

[charlesonyekanne]

I created a subdomain from my webhost for a folder in my public_HTML and I found it difficult to link a working subdomain to it.
My primary domain is chalypage.com then subdomain is Grasp, its been over some days now I created the
Subdomain. And the Name server of my primary domain is pointed to Cloudflare CDN. Am finding it difficult to makey subdomain work fine. Below is the error I got from HTTP while trying to check it.

Not Found

The requested URL /404.html was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Apache Server at grasp.example.com Port 443

[MarkMeyer]

Your Apache is not configured to handle that request.

You’d do this either in your Apache vHost config, or with .htaccess

RewriteEngine on
RewriteCond %{HTTP_HOST} ^sub.domain.com
RewriteRule ^(.*)$ http://domain.com/subdomains/sub/$1 [L,NC,QSA]

Or try a Page Rule

https://sub.dom.ain
Forwarding URL, 301
https://sub.dom.ain/sub/folder/

[charlesonyekanne]

Still not working, I have added the rewrite rules