IPSec VPN with Squid Proxy
I currently have a pfSense VPN setup to accept connections from remote certificate-based IPSec VPN clients. The VPN is in the AWS cloud and has no hosts behind it. It simply has a WAN interface configured.
WITHOUT Squid enabled, these users can create the VPN connection and browse the web. The VPN routes the traffic back out the WAN interface.
When I enable Squid as a transparent proxy the devices can no longer browse the web.