My VPN Disconnected When the Phone Locked—So the Message Arrived Fourteen Minutes Late

I unlocked my phone in the back of a taxi and watched six messages arrive at once.

The first said:

The client approved the final version.

The last said:

Are you still there? We need your answer now.

I had been waiting for that approval since leaving the airport. The campaign was scheduled to launch at 6 p.m., and the production team needed my confirmation before releasing the files.

Fourteen minutes earlier, I had checked that the VPN was connected, placed the phone in my pocket and assumed the message would appear on the lock screen.

It never did.

When I unlocked the phone, the VPN application displayed Reconnecting. A few seconds later, the delayed messages flooded in.

I blamed the taxi’s mobile signal. We had driven through a tunnel and changed cell towers several times. But the phone still had service, and my navigation app had continued updating.

To test it, I reconnected the VPN, asked a colleague to send another message and locked the phone.

Five minutes passed.

No notification.

I woke the screen. The VPN reconnected, and the message appeared.

The app worked perfectly while I was looking at it. The moment the phone went dark, the protected connection quietly stopped being useful.

Locking the phone changes more than the screen

I had treated the lock button as a cosmetic action. The display turned off, but the phone was still on, so I expected every connection to continue as before.

Modern phones become much more selective once the screen is dark.

Android uses power-saving systems such as Doze and App Standby to reduce background processing and network activity while a device is idle. A VPN must remain active within those restrictions rather than behaving like an ordinary background app. (Android Developers)

That creates a frustrating chain of events:

The screen turns off.

The operating system reduces background activity.

The phone moves between Wi-Fi, mobile towers or lower-power radio states.

The VPN tunnel becomes stale or disconnects.

Android’s always-on protection blocks applications from using an unprotected route.

Messages wait until the tunnel returns.

From a privacy perspective, blocking ordinary traffic is better than allowing it to escape. From the user’s perspective, the result looks like a broken phone: no messages, no calls and no warning until the screen is unlocked.

That distinction mattered. My kill switch was not necessarily failing.

The VPN was failing to recover while the phone remained locked.

The obvious settings fixed only the easy version

The VPN I normally used was an established provider with years of public history, a large support operation and servers in dozens of countries.

Those were sensible reasons to trust it, so I tried to repair the setup before replacing it.

I changed the app’s battery setting from Optimized to Unrestricted. I allowed background data. Then I enabled Always-on VPN and Block connections without VPN.

With the screen awake, everything looked correct.

Messages arrived.

A speed test was fast.

The VPN icon remained visible.

Then I locked the phone and placed it on the table.

Several minutes later, a colleague called me through our work messaging app. The other phone rang normally. Mine remained silent.

When I woke the screen, the VPN moved from Connecting to Connected. The missed-call notification appeared immediately afterward.

I tried another server, then another protocol, then the provider’s automatic mode.

The timing changed slightly, but the pattern remained. The service worked while the phone was active and often waited for the screen to wake before restoring the tunnel.

Other Android users describe the same practical frustration: the VPN disconnects after the device sits idle and returns only after the app is opened again. (Reddit: r/ProtonVPN) The provider name was less important than the consequence. An “always-on” connection still depended on someone noticing that it had disappeared.

That was exactly what I could not do while the phone was in my pocket.

More servers could not solve a background problem

My first instinct was still to change location.

Perhaps the nearest server was overloaded. Perhaps another city would respond faster when the phone woke. Perhaps the automatic mode was choosing poorly.

But every server worked while I was actively testing it.

The failure happened later, after the screen locked and the network changed underneath the tunnel.

That changed the comparison.

Server count helps when one destination is crowded or unreachable. It matters far less when the application stops maintaining the route as soon as the phone becomes idle.

The speed test was equally misleading. The VPN could move plenty of data while the display was on. My urgent task required something smaller and harder: keep a quiet connection alive long enough for one approval notification to reach the lock screen.

The real problem was not speed.

It was background recovery.

The smaller app passed the test with the screen off

I had OnlydogVPN installed as a travel backup.

It has fewer server locations than the established provider, a shorter public history and fewer independent reviews. That would matter if I regularly needed an address in a specific small city.

I did not need a city.

I needed the next message to arrive before I touched the phone.

The smaller app organised its choices around situations instead of opening with a map. I selected the option for a weak or changing mobile network, left Android’s always-on protection enabled and connected.

Then I asked my colleague to repeat the test.

I locked the phone.

The display went dark.

A few minutes later, the phone vibrated on the table.

The message was already visible on the lock screen:

Test one. Screen still off?

I left the phone untouched and asked for another.

That notification arrived too.

The next test was harder. I started a voice call, locked the phone and walked from the hotel lobby toward the lift. As I moved away from the lobby, the phone left Wi-Fi and changed to mobile data.

The audio softened for a moment.

The call continued.

Finally, I locked the phone during a file download and switched off Wi-Fi from another device. The transfer paused briefly while the cellular route took over, then continued without making me reopen the VPN.

For the first time that day, locking the phone did not mean abandoning the protected connection.

The technology appeared as a notification

The service uses an HTTP/3-based transport with additional traffic obfuscation.

HTTP/3 runs over QUIC, which is designed to recover efficiently when packets are lost or the underlying network changes. (RFC 9308) That suits a phone because locking the screen often coincides with exactly those changes: Wi-Fi weakens, the radio enters a lower-power state, or the device moves between networks.

I could not observe the phone manufacturer’s internal power-management decisions or the carrier’s routing rules. What I could observe was the result.

The established provider frequently waited for the screen to wake before rebuilding a useful connection.

The smaller app recovered while the screen was still dark.

Its value was not a more convincing status icon. It was the message already waiting on the lock screen.

That became the comparison criterion that mattered.

The real approval arrived during the second test

I rejoined the production chat and put the phone back in my pocket.

The taxi had reached the city centre. Signal strength changed every few blocks as we passed between tall buildings. This time, I resisted the urge to keep the display awake and watch the VPN icon.

Three minutes later, the phone vibrated.

The client had requested one final change to the Japanese subtitle. The editor attached a corrected file and asked whether it could replace the existing version.

I reviewed the sentence, approved it and returned the phone to my pocket.

A few minutes later, the production confirmation appeared on the lock screen:

Updated. Launching now.

No delayed burst of messages.

No manual reconnection.

No discovery that the campaign had been waiting while the phone silently sat offline.

The original task was complete.

Only afterward did I notice a smaller convenience. When I reached the hotel and opened my laptop, the service let me link the second device with a verification code instead of entering another email-and-password account on the hotel network.

That feature had not delivered the locked-screen notification. The launch was already moving.

But it allowed me to continue working on a larger screen without creating another login problem, which gave me a reason to keep the service installed after the emergency had passed.

What to check when a VPN disconnects after locking the phone

On Android, begin with the operating system rather than the server list.

Open the VPN app’s battery settings and remove background restrictions. Check whether the phone manufacturer has additional controls for sleeping apps, battery management or automatic optimisation. Confirm that background data is allowed.

Then enable Android’s Always-on VPN option. For stronger protection, use Block connections without VPN, understanding that the phone may appear completely offline if the tunnel fails to return.

After that, test the behaviour that matters.

Connect the VPN, lock the phone and send it a message from another device.

Wait several minutes.

Try a voice call.

Move from Wi-Fi to mobile data while the screen remains off.

Do not judge the result after reopening the VPN app. The question is whether the notification arrived before you touched the phone.

Apple devices handle background VPN behaviour differently, but the practical test remains the same: lock the phone, change networks and check whether the protected task continues without manual intervention. (Android Developers)

My established provider still offered more locations, a longer history and more advanced controls. Those advantages remained real.

They did not deliver the approval while the phone was in my pocket.

The smaller service offered fewer choices, but it maintained the protected route through the locked-screen period and the Wi-Fi-to-mobile handoff.

The VPN I needed was not the one that performed best while I stared at its app. It was the one that delivered Launching now while the screen was still dark.