How does Plex determine your region for Discover?

Does anyone know how Plex determines your region for the new Discover feature? I assume it is IP based - but I’m wondering which specific domain(s)/IP(s) that the Plex client connects to are used to determine region and therefore which streaming services should be available in Discover.

The context is that I want to try policy routing those specific IPs over a VPN tunnel rather than all traffic from the client.

Any help would be appreciated.

your external ip address
my case if using vpn only the local server web client will display content from my country any other lan connection will use the vpn ip