[PHX] Make a subdomain instead of IP for client?

Hello,

Instead of using my proxy IP in my client.php I'm trying to setup a subdomain such as derp.site.com - I've created it in CF (cloudflare..) and pointed it to my TCP Proxy, added it in IIS as I was told to, how ever when I set it in my client.php the client doesn't load.

I'm wondering, do I have to add it in my Emulator config instead of using the IP? So instead of it being for instance 127.0.0.1 it'll be derp.site.com ? I've seen it on other places just can't quite get my head around it. I'm using Phoenix btw. Anyone any ideas?

Cheers amigos.