In short: When no VPN works on your phone, five system-level causes cover the vast majority of cases: the Android 16 OS bug (updating a VPN app via Play Store while it's active breaks all VPN tunnels), an MDM profile blocking VPN creation, aggressive battery optimisation, carrier UDP port blocking, or a conflict between two VPN or DNS apps. Rebooting fixes around 40% of cases instantly.
When every VPN app fails at once, the problem is never "bad luck with multiple apps" — it's always something at the OS, profile, or network layer. To accurately check whether your VPN is working, you need layered diagnostics, not app-swapping. Here's a structured breakdown of all five causes.
Why No VPN Works — 5 System-Level Causes
All VPN apps failing simultaneously always points to a system-level problem. Use the table below to find your symptom and start with the right fix.
| Symptom | Most Likely Cause | First Step |
|---|---|---|
| Everything worked, then stopped — no settings changed | Android 16 bug (Play Store update while VPN was active) | Reboot the device |
| Add VPN button greyed out, section inaccessible | MDM profile blocking VPN creation | Settings → VPN & Device Management (iOS) / Security (Android) |
| VPN connects but drops after 1–2 minutes in background | Battery optimisation killing the process | Remove battery restrictions for the VPN app |
| Fails only on office or hotel Wi-Fi, works at home | Network blocking VPN protocol UDP ports | Switch to IKEv2 or OpenVPN TCP protocol |
| VPN shows "Connected" but websites won't load | Conflict with another VPN or DNS app | Disable all DNS filters and antiviruses with a VPN feature |
Android 16 Bug: How a Play Store Update Kills All VPNs at Once
The most common cause in 2026 is a confirmed Android 16 system bug: updating a VPN app via Play Store while it's actively running breaks VPN connectivity for every app on the device. Mullvad, Proton VPN, WireGuard, and TunnelBear have all confirmed the issue independently.
How It Manifests
A typical scenario: VPN was working fine, Play Store silently updated the client in the background — and from that point on, no VPN app can establish a tunnel. The app freezes at "Connecting…" indefinitely or reports "Connected" while no traffic actually flows: websites fail to load, apps show no connection. Regular internet without VPN works normally. The issue affects every VPN app installed on the device — not just the one that was updated.
What's Happening Technically
According to Android Authority, Tom's Guide, and TechRadar, the defect is in the Android 16 network stack: after a VPN app updates "live," the OS blocks its access to the network interface at the system level. The VPN client continues running from its own perspective, but the TUN adapter (the virtual network interface VPN uses) stops passing traffic in either direction. VPN app developers cannot fix this bug — it's in Android, not in the app.
Temporary Fix Until Google Patches It
The only reliable fix is a device reboot. After rebooting, VPN works again — until Play Store next updates it while it's active. Preventive steps: disable auto-updates for your VPN app in Play Store (Play Store settings → Auto-update apps → "Don't auto-update apps"), and update it manually after disabling VPN first. For more on VPN issues on Android, see the dedicated guide.
MDM Profile and Parental Controls: VPN Blocked by Administrator
An MDM profile (Mobile Device Management) can fully prohibit VPN configuration creation — this is standard corporate security policy. If the Add VPN button is greyed out or the settings section is inaccessible, this is almost certainly the cause.
iOS Supervised Mode — Why VPN Is Grey and Unavailable
In supervised mode, an organisation's MDM profile can apply a restriction that prevents users from adding their own VPN configurations. After iOS 18, several MDM systems including Jamf and Microsoft Intune started applying this restriction automatically — the Add VPN button went grey without warning, even on devices where VPN had worked before. How to check: Settings → General → VPN & Device Management. If you see a "Device Management" entry with your organisation's name, VPN creation may be policy-blocked. Contact your IT administrator — only they can modify the policy or provide the approved corporate VPN client.
For more on configuring VPN on iPhone, see the dedicated guide.
Android Work Profile and Corporate Policies
On corporate Android devices with a work profile, MDM policy can block VPN creation in the personal profile or restrict it in the work profile. If the device is enrolled in a DPC (Device Policy Controller) system, the OS may force-install a corporate VPN client that conflicts with third-party VPN apps.
How to Check Whether Your Device Has an MDM Profile
iOS: Settings → General → VPN & Device Management — a "Device Management" entry means an MDM profile is installed. Android: Settings → Security → Device Administrators (path varies by manufacturer and Android version) — an app from your employer in the list means MDM. Removing an MDM profile from a managed device typically requires an admin PIN or will factory-reset the device; it cannot be removed unilaterally.
Aggressive Battery Optimisation — The Silent VPN Killer
Battery optimisation is one of the most common and least obvious causes: VPN works fine with the screen on but disconnects within minutes once the screen turns off. This is especially prevalent on Android devices with custom OEM launchers.
Android Doze Mode and Adaptive Battery
Since Android 6.0, Doze mode restricts background network activity when the screen is off and the device is stationary. VPN services are typically exempt from this restriction via the VPN service API, but this protection can break in Android 16 due to the known bug. Adaptive Battery (Android 9+) additionally "learns" to kill apps it considers rarely used — and can erroneously restrict a VPN client running silently in the background.
OEM Restrictions: Xiaomi, Huawei, Samsung, OnePlus
Device manufacturers layer their own aggressive battery management on top of standard Android Doze. Settings paths by manufacturer:
| Manufacturer | Settings Path | What to Do |
|---|---|---|
| Xiaomi / Redmi / POCO | Settings → Apps → [VPN app] → Power control | Select "No restrictions"; enable Auto-start and Background activity |
| Huawei / Honor | Phone Manager → App launch → [VPN app] | Switch to "Manage manually" → enable Auto-launch and Background running |
| Samsung | Settings → Device Care → Battery → Background activity limits | Remove VPN app from Sleeping apps and Deep sleeping apps |
| OnePlus / OPPO / Realme | Settings → Battery → Battery optimisation → [VPN app] | Select "Don't optimise" |
| Google Pixel | Settings → Apps → [VPN app] → Battery | Select "Unrestricted" |
How to Remove VPN from Battery Optimisation
Universal path on most Android devices: Settings → Apps → [VPN app] → Battery → Unrestricted. This allows the VPN process to run in the background without system interference. If VPN still disconnects after the screen turns off, check the OEM-specific settings from the table above — manufacturers often add an extra restriction layer on top of standard Android battery management.
Carrier or Network Blocking VPN Protocols
If VPN fails only on a specific network (office, hotel, university, public Wi-Fi) but works fine at home or on mobile data, the problem is the network — not your device.
UDP Port Blocking
WireGuard uses UDP port 51820 by default. OpenVPN uses UDP 1194. Both are non-standard ports and are frequently blocked by corporate and hotel firewalls. If the protocol uses UDP and the network blocks it, packets never reach the VPN server and the tunnel cannot form. Switch to IKEv2/IPSec (UDP 500 and 4500 — far more commonly permitted on corporate networks) or OpenVPN in TCP 443 mode (the standard HTTPS port, almost never blocked since blocking it would disable all web traffic).
Corporate Wi-Fi and Captive Portals
Corporate networks may also use DPI (Deep Packet Inspection) to detect VPN traffic by protocol signature — even if the port is technically open. Captive portals (login pages on public Wi-Fi) block all connections until you authenticate: always complete the portal login before launching your VPN.
What to Try: Protocol and Network Switching
- Switch from Wi-Fi to mobile data. If VPN works — the issue is definitely that Wi-Fi network.
- Change the protocol in your VPN app to IKEv2 or OpenVPN TCP.
- Try a different server from your VPN provider.
- If the network uses a captive portal, complete the login before launching VPN.
App Conflicts and Permissions
Both Android and iOS allow only one active VPN tunnel at a time. When multiple apps compete to control device traffic, they conflict — and none works correctly.
Two Active VPN Apps Simultaneously
Android automatically terminates the previous VPN when you activate a new one, but after an app crash, a VPN process can get stuck holding the network interface. Check: Settings → Network → VPN — there should be no "active" connection you didn't enable yourself. On iOS, the VPN icon in the status bar disappears when VPN is off; a full reboot clears all stuck states.
Antivirus or DNS App Intercepting Traffic
Antiviruses (Kaspersky, Norton, Avast) and DNS filters (AdGuard, NextDNS in VPN mode) all use the same VPN OS interface. When you launch your VPN client, the system must choose which app controls traffic. If the antivirus claimed the VPN slot first, your VPN client cannot get it. Temporarily disable the antivirus and any DNS filter, then check whether your VPN works. If it does, look for a "Don't use VPN API" option in the antivirus settings, or switch the DNS filter to a VPN-free mode (local proxy or DoH without a tunnel).
Outdated VPN Profile in System Settings
Old VPN profiles added manually through system settings can conflict with new ones. iOS: Settings → General → VPN & Device Management → VPN — delete all outdated profiles. Android: Settings → Network → VPN — tap the gear icon next to an entry and delete it.
5-Step Diagnosis: Find the Cause in 5 Minutes
Work through these steps in order — each takes 1–2 minutes. The first step that fixes the problem tells you exactly what the cause was.
- Reboot the device. Rebooting eliminates the Android 16 bug and clears all stuck VPN processes. VPN providers report this fixes approximately 40% of cases immediately. If VPN works after a reboot, the cause was the OS bug or a stuck process.
- Check for MDM profiles. iOS: Settings → General → VPN & Device Management. Android: Settings → Security → Device Administrators. An organisation profile may indicate policy-level VPN blocking — contact your IT admin.
- Remove battery restrictions. Settings → Apps → [VPN app] → Battery → Unrestricted. On Xiaomi/Huawei, also enable Auto-start and Background activity per the table above.
- Check for app conflicts. Make sure no second VPN app, DNS filter (AdGuard, NextDNS), or antivirus with a VPN feature is running at the same time. Close conflicting apps and retry.
- Switch networks or reset network settings. Switch from Wi-Fi to mobile data. If that works, the issue is network-side — change the VPN protocol. Last resort network reset: Android — Settings → System → Reset → Reset Wi-Fi, mobile & Bluetooth; iOS — Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings. After the reset, reconnect to Wi-Fi and reconfigure your VPN.
If all five steps fail and VPN still doesn't work, contact your VPN provider's support team. LiMP VPN users get priority technical support for all Android and iOS issues.
Frequently Asked Questions
Why does no VPN work on my phone when everything was fine before?
Most likely the Android 16 bug (a Play Store VPN app update breaks the OS-level tunnel for all VPN apps) or aggressive battery optimisation. Try rebooting your phone and removing battery restrictions for the VPN app — this resolves most cases.
How do I check if VPN is blocked by an MDM profile on iPhone?
Go to Settings → General → VPN & Device Management. If the Add VPN button is greyed out or the section is inaccessible, a corporate or school MDM profile is blocking VPN configuration creation. Contact your IT administrator.
What if no VPN works on either Wi-Fi or mobile data?
This points to a device-level problem: an MDM profile, a conflict between two VPN apps, or an OS bug. Check VPN app permissions: Settings → Apps → [VPN app] → Permissions — the "VPN" permission must be granted. If another VPN app or DNS app is running, disable it first.
Which VPN protocol works on corporate or public Wi-Fi networks?
WireGuard and OpenVPN use UDP by default, which is often blocked by corporate and public networks. If UDP is blocked, switch to TCP mode (if your VPN app supports it) or use IKEv2, which passes through NAT and corporate firewalls more reliably.
Does resetting network settings help when no VPN works?
Sometimes, yes. A network reset removes corrupted VPN profiles and DNS entries. After the reset, you'll need to rejoin Wi-Fi networks and reconfigure your VPN. Android: Settings → System → Reset → Reset Wi-Fi, mobile & Bluetooth; iOS: Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings.