VPN clients work in different ways:
- Some VPN clients create TAP adapters in Network and Sharing center
- Some VPN clients, alter the DNS settings in order to work.
- If the VPN creates a TAP adapter, then Heimdal will not be able to apply the 127.7.7.x on the IPv4 on it and the traffic will not be filtered.
- If the VPN sets its own DNS and overwrites the one set by Heimdal Security, then the traffic will not be filtered.