I'm looking for an Android app with the following features:
- Does not require root
- Acts a firewall (can use VPN)
- Acts as a global ad-blocker, preferably with user-defined lists (similar to AdAway, but without requiring root)
- Runs on KitKat devices
NetGuard meets all of these requirements, except the last one.
Prefer gratis and open-source, but open to all answers.
Unlike this related question, firewall functionality is needed.