I installed Wordpress Multisite onto a site with the www. prefix today.
(using the sub-folder method, softaculous auto picked this)
When adding a Custom Domain in the child site domain mapper it works fine if I add a domain but if I use a www. prefix + the domain it fails to detect the site.
It just redirects to the home page of the master site.
Should I have not used www. in the master main site install? Or can this be fixed.