The in-app tracking filter installs its own local VPN profile to perform on-device security checks.

Since iOS currently does not support multiple active VPN profiles, most VPNs stop working once our filter is enabled and vice-versa.

The good news is that there's a setup that might enable your VPN to run alongside 1Blocker's profile on some devices.

If your VPN occupies a slot in the Personal VPN section in iOS Settings > VPN and uses the IKEv2/IPsec protocols, it might become compatible with our VPN profile. The in-app blocking filter must be set to DNS Proxy mode in the (...) menu at the top right of the filter.

Even though there's no guarantee that this configuration will work out as expected due to iOS limitations, it's still worth giving it a try.