WordPress Multisite: Restrict User Registration to Network

Hi,

I created my WordPress Multisite this week. In doing so, it created the network domain of example.net instead of my original site domain of http://www.example.net

I also created a new site in my network at members.example.net. This site is where my business team will access members only resources and information. I've setup all of the login/registration pages using Ultimate Member. It is working beautifully, but...

If team members and/or visitors go to our public site - http://www.example.net - and type "example.net" instead, they are directed to a network registration page. This allows them to register for a network account.

I've had 2 team members register on this network site rather than on the members site.

Is there a way to tell WordPress to go to a different site instead of example.net? A redirect to our public site, http://www.example.net? Or not allow user registration on the network, but only on the members site? If a user needs network access, I want to be the only one to register users to the network while still allowing users to register for the members site.

I've tried to include as much information as possible. Please let me know if there is any other information needed. Thanks!