Why does Firewall AI use a VPN service and why can't it run together with other VPN apps?

Firewall AI uses an internal VPN service on Android so the app can locally route, monitor, block, and selectively allow all traffic on your device. Protectstar explicitly describes this internal VPN service as a local security mechanism that works as a proxy between apps and their connection servers.

The key difference from a traditional VPN is this: Firewall AI's internal service is not a conventional VPN that creates an encrypted connection to an external VPN server or replaces your IP address for geo-blocking or anonymity. Protectstar explicitly states that Firewall AI does not connect to external VPN servers; instead, it works locally only as a protective layer on the device.

This approach is exactly what makes the firewall technically powerful: according to the product page, Firewall AI routes traffic through a dedicated VPN access point so connections become visible and the app can control them based on rules, filter lists, and security logic. That is the basis that allows Firewall AI to block unwanted outbound connections, suspicious communication, and other risky network activity.

So why can't Firewall AI run alongside another VPN? Here again, Android is the decisive factor: according to Android Developers, there can only be one active VPN service per user or profile, and starting a new VPN service ends the existing one. That is why Firewall AI cannot be operated at the same time as other VPN apps. Protectstar explicitly names examples such as NordVPN, Mullvad, and IVPN.

In short: Firewall AI uses Android's VPN mechanism not to connect you to a third-party VPN server, but to control and protect all of your traffic locally. That is exactly why this internal VPN service is technically necessary—and exactly why Android blocks simultaneous operation with a second VPN app.