[Plugin: WordPress MU Domain Mapping] Clicking backend link in Site Admin redirects to home page rat

Using WPMU and Domain Mapping plugin both for the first time…

After getting myself a step from the finish line, I am stuck.

I get to the point where the plugin is installed and I’m ready to add my subdomains. I add the first subdomain and then…

In the Site Admin section, under Blogs, I click “backend” for the added subdomain. Once in the backend, I go to Tools -> Domain Mapping and map sub.domain.com to sub.com.

I test the redirection and it works.

However, for some reason, when I am back in the Site Admin -> Blogs section of the primary domain and I click the “backend” link for the subdomain, it redirects me to the home page of that subdomain and I can no longer get into the backend.

The backend link is being expressed as sub.domain.com/wp-admin and this is redirecting to the home page. Specifically, it redirects to sub.com/?dm_gotoadmin=1&back=%2Fwp-admin%2F.

Does anyone have an idea what is going wrong here? Am I even making sense? Probably not. Any help you can give is much appreciated. Thanks!

https://www.ads-software.com/extend/plugins/wordpress-mu-domain-mapping/