Seriously you guys are not aware of AFWall+ ?
Seriously, have you not read this thread?
First, there was
DroidWall, which was unceremoniously discontinued and not fit for use for any Android OS past Gingerbread.
Next, the same developer launched
Android Firewall. Not only did the developer also discontinue this firewall and drop it from Google Play without notice, but it appears
Android Firewall now lets ads through! Note that this does not happen if you block Android Firewall in Android Firewall, so it might be that the developer deliberately modified the firewall to let ads through - someone with more knowledge would have to verify this.
Now, the same developer has released
AFWall+. I'm sorry but I can't trust a firewall from a developer that has a history of abandoning their apps, especially a security app.
In each case, the developer went dark.
So now many are looking for a firewall that has been supported for a long time, and we are willing to pay for it. I don't think we are being unreasonable here, I appreciate the work that developers have done for the community but would be respectful of users if the app was discontinued with some notice and explanation, rather than leaving users vulnerable.