Brand new to the forum and to NGINX so please be gentle....

Using NGINX Plus to be a load balancer for a .NET web application running on windows servers. We use subdomains to separate environments. We would like to implement IP whitelisting based on the domain. So:

environment1.example.com
environment2.example.com
environment3.example.com

192.168.1.1/24 should be able to access all environments <- Default config allows this
192.168.2.1/24 should be able to access environment 2 only <- This is the scenario we can't seem to solve (though we believe we can write a custom LUA script to do it, we would like to avoid that)
192.168.3.1/24 should not be able to access any environments <- Figured out several ways to do this, easiest is to use DENY directive in server block.