I have 3 different WordPress sites on my host provider in a linux shared hosting package. The main domain is domain-a.com. A secondary add-on domain is domain-b.com. I have a parked domain domain-c.com that redirects to domain-b.com.
All are registered elsewhere and the a-record points to this host provider. Here's the problem: when a user types domain-c.com it properly redirects to domain-b.com. No problem there. The problem occurs when a user types domain-c.com/something.html (anything that is not found on the domain-b.com). It produces my error404 page for domain-a.com, not domain-b.com.
I am told by the host providers (at the registrar and this host) that this is a WordPress issue because of the htaccess file and how WP resolves the domains.
I have tried a plugin named Simple 301 Redirects but it has no effect here.