Problem creating new subdomain on new Multisite install

I'm really at my wits end. Having spent a good 4 hours installing multisite with DNS change to be able to use subdomains, I now get 404 errors when going into the Dashboard of the new site.

Having looked around lots of people have this problem and usually is the .htacces..

The code I have in there is what I got from my original setup:
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

I've tried the other codes that are around but nothing is helping.

I'm can't progress any further.

Can anyone help soon please.