Android: Always-on VPN, battery, Private DNS
How ForestVPN works with Android's Always-on VPN, battery optimization and Private DNS, what its own checks look at, and what ForestVPN does not publish.
This page covers three Android settings that affect how ForestVPN behaves: Always-on VPN with Block connections without VPN, battery optimization, and Private DNS. It states what the app itself does and checks. Where ForestVPN has no published guidance, it says so.
Symptoms
- ForestVPN disconnects or keeps reconnecting after the screen has been off for a while.
- Traffic is not blocked when ForestVPN is stopped.
- The app says the VPN permission is missing, or another app holds the always-on slot.
- Pages stop loading after you pick a Private DNS setting.
Likely causes
- Battery optimization. If Android limits ForestVPN in the background, the app has to keep reconnecting you. The app's own diagnosis checks for this and flags it as a warning when Android is still limiting the app in the background.
- Android's own Always-on VPN is not set. ForestVPN has a setting that blocks traffic while the tunnel is down, enforced by Android while ForestVPN is running. When the app itself is stopped, only Android's own Always-on VPN with Block connections without VPN covers the gap. Neither is absolute.
- Another VPN app holds Always-on. The app's permission check reports a failure when a different app is the Always-on VPN.
- Private DNS in strict mode. The app's diagnosis checks the phone's Private DNS mode and shows a warning when it is strict.
Fix each cause
Battery optimization. The first time it matters the app asks "Skip battery optimization for ForestVPN?" and explains that this lets it keep running in the background so it does not have to keep reconnecting you. Say yes to that prompt, or open the app's assistant, run the diagnosis, and use its Open battery settings button. In Android's battery page, pick the option that puts no limit on ForestVPN.
Always-on VPN and Block connections without VPN. For the strictest setting, open Android's VPN settings, pick ForestVPN as the Always-on VPN, and switch on Block connections without VPN. With that on, Android blocks traffic even when the app is stopped. While traffic is blocked nothing has internet; reconnect ForestVPN to get online again.
Another app is the Always-on VPN. Open Android's VPN settings and pick ForestVPN there, then reconnect.
Private DNS. The app's diagnosis only reports the mode and offers a shortcut to the phone's network settings. ForestVPN has not verified how each Private DNS setting affects the app and publishes no guidance on which setting to pick. If pages stop loading, write to support with a support code and say which Private DNS mode is set.
Still stuck
Write to support with a support code from Account → Get help. Never send your account number. Say what the screen showed, for example the connection state the app named.