Private networking is available on most servers. We are currently transitioning our data centers to be able to offer this service. Right now, our private network is available to customers with dedicated servers in our Lenoir, North Carolina data center. We are still in the process of rolling this out. 

VPS customers do not currently have private network access. We are working on adding this soon.

Just because it appears your server does not have private networking, you might actually have the service available. Please open a ticket with support to verify. A private VLAN may need to be assigned to you.