Stop wp-signup.php

I had this accomplished on my other setup, however for some reason I cannot figure out how to do it for this one, I had a tutorial I followed, but that has long since been lost.

I have to set up numerous wp-multi-sites, so getting this back to the core registration would be great. It would make my product sellable.

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my goal is to stop wp-login.php?action=register from being redirected to wp-signup.php

Simple as that.

I just want to use the default registration form for the multisite, and I need it to be this.

So a step by step on how to accomplish this would be awesome, been googling/binging for hours and hours.

Thanks in advance!