I have heard good things about this one. But i think this one of those no root firewalls that uses the vpn, so I figure this means I can't use a VPN at the same time.

An alternative android root only option is afwall+ which allows blocking on lte, WiFi, lan, and VPN separately, and script access to iptables. Not sure how actively developed it is, but it seems to work ok.

*edit: Seems to still be active, open source, and available on fdroid too.

https://github.com/ukanth/afwall

Netguard is fantastic, although it takes a while to get a safe setup working. I'm blocking traffic by default and get to see all the blocked connection attempts - the extent to which apps transmit data to various parties is depressing. Netguard should be a standard OS feature.

I didn't want to pay without testing the features first, so I have rebuilt the app (it is opensource) with Pro enabled, so I guess that's an option if you want to avoid payment. Updates are a problem then though. Once I tested it I gladly paid (more than requested) to support the development. I never got around to reinstalling it though, so I'm still on an older version.

NetGuard is simply awesome. The piece of mind when I know which servers the apps are contacting, and being able to block their access to the net by default, is just great. The rules could be made a bit more easily adjustable (it would be nice if I could block `*.firebaseinstallations.googleapis.com` everywhere, even if other traffic is allowed for the app), but I'm just nitpicking now. Highly recommend it.

"Small payment" is an understatement :)

"You can get all current and future NetGuard pro features (including updates) without Google Play services for the GitHub or F-Droid version by a one time donation of € 0.10 or more. If you donate 7 euros or more, you can activate the pro features on all Android devices you personally own, else you can activate the pro features one time only."