Work down this list. It is ordered by how often each cause turns out to be the real one.
1. Check the internet works without the VPN
Disconnect the VPN and load any website. If nothing loads, the problem is the connection, not the VPN. If a kill switch is blocking traffic, turn it off temporarily to test — most apps have a pause option.
2. Change the server
Individual servers fail, fill up or get blocked. Pick a different city in the same country, then a different country. If a different server connects, the first one was the problem and there is nothing else to fix.
3. Change the protocol
This resolves more cases than anything else on the list.
- Slow or dropping: switch to WireGuard, NordLynx or Lightway.
- Will not connect at all on a restricted network: switch to OpenVPN TCP on port 443, which looks like ordinary HTTPS traffic.
- In a censored country: switch to the provider’s obfuscated mode — NordVPN’s obfuscated servers or NordWhisper, Proton’s Stealth, ExpressVPN’s automatic obfuscation, Mullvad’s bridges, Surfshark’s Camouflage.
4. Connected, but no internet
Almost always DNS. Turn on the app’s “use VPN DNS” or “DNS leak protection” setting. On Windows, also disable Smart Multi-Homed Name Resolution, which sends queries out of every adapter at once. Then confirm with the leak test.
If DNS is fine and pages still do not load, the tunnel is being throttled rather than blocked — the standard behaviour of national firewalls. Go back to step 3 and use obfuscation.
5. Sign out and back in
Subscription lapsed, device limit reached, password changed on another device. The app usually reports this badly or not at all. Signing out and in reveals it in a sentence.
6. Phone-specific: stop the system killing the app
iPhone: turn on the app’s Always-On or on-demand setting so iOS maintains the tunnel rather than the app. Settings → General → VPN & Device Management shows the profile; if it is missing, reinstall the app and accept the configuration prompt.
Android: Settings → Network & internet → VPN → the gear icon → Always-on VPN and Block connections without VPN. Then exclude the VPN app from battery optimisation. Xiaomi, Huawei, Oppo and OnePlus have extra app-killers with their own settings.
7. Desktop-specific: reinstall the driver
On Windows, a broken WireGuard or TAP adapter causes connection failures that survive every other fix. Uninstall the app, reboot, and install the current version from the provider’s own website. On macOS, if the app asks for a system extension permission, approve it in System Settings → Privacy & Security; a denied extension means no kill switch and often no connection.
8. Look at what else is on the machine
Antivirus and firewall products intercept VPN traffic more often than any of them admit. Temporarily disable the antivirus’s network or web-shield module and try again. On a work machine, a corporate VPN or endpoint agent will conflict with a personal one; they cannot both hold the default route.
9. Check whether it is the country, not you
If you are in China, Iran, Russia, Turkey or the UAE, and the app connects but nothing loads, or the app cannot even fetch its server list, the network is the cause. The country guides list which providers currently work and which modes to use, and the pre-travel checklist explains why installing before arrival matters: in all five, the providers’ own websites are blocked.
Still stuck
Note the exact behaviour — connects and drops after N seconds, never connects, connects with no traffic — and send it to the provider’s support with the protocol and server you used. That description gets a useful answer; “it doesn’t work” does not.