All of the documentation I've read says that when you create a network template, you can tell it what range of IP addresses to use for the subnets on the MX Addressing and VLANs page. For example, giving it the range of 10.5.0.0/16 and telling it to create /24 subnets from that /16 block. When I create a template, or edit an existing template, there is no such field in the GUI. Is there something I have to set somewhere to make that field available?