Net Blocker - Firewall per app

Net Blocker allows you to block specific apps from accessing the Internet without root requirement.
PLEASE read the descriptions below carefully before using.
As you known, there are apps and games which may:
• Access the Internet only to display ads or steal your personal data
• Continue to access the Internet in the background services even when you exited
Therefore, you should consider to block apps from accessing the Internet to help:
★ Reduce your data usage
★ Increase your privacy
★ Save your battery
Features:
★ Safe and easy to use
★ No root required
★ No dangerous permissions
★ Support Android 5.1 and up
PLEASE note that:
• This app only sets up a local VPN interface to be able to block the network traffic of apps without root. And it does not request the dangerous permissions such as Location, Contacts, SMS, Storage,... So, you can trust that it does not connect to a remote server to steal your privacy data. Please feel safe to use!
• Because this app is based on VPN framework of Android OS, so if turned it on you cannot use another VPN app at the same time and it may drain the battery.
• Even when apps and games are blocked from accessing the Internet, they can still display ads loaded from cache memory. So, you also need to clear their cache to be able to hide ads.
• Some IM apps (Instant Messaging apps, such as WhatsApp, Skype) may use Google Play services to receive the incoming messages if the app has no network. So you may also need to block "Google Play services" to block receiving messages for IM apps.
• Battery Optimization feature of Android OS may auto disconnect VPN apps in the sleep mode to save battery. So you may need to add Net Blocker app to whitelist of the battery optimization to keep it working.
• This app can't block Dual Messenger apps because Dual Messenger is a feature of Samsung devices only and it does not support VPN fully.
If you have any questions or suggestions, please contact me at thesimpleapps.dev@gmail.com
FAQ:
• Why can't I press "OK" button of the dialog?
This problem may be caused by using an app that can overlay other apps, such as blue light filter apps. Those apps may overlay the VPN dialog, so that cannot press "OK" button. This is a bug of Android OS which needs to be fixed by Google via an OS update. So if your device hasn't fixed yet, you may need to turn off the light filter apps and try again.