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VPN leak in one browser? How to diagnose it

Find out why a VPN leak appears in one browser, compare the affected browser with a clean profile, and fix settings or extensions safely.

Kevin DoyleHardware tests Tests 4 min read

Your VPN appears connected, but a leak test flags one browser while another looks fine. That difference can come from a browser extension, profile setting, or the way the VPN handles WebRTC or IPv6. It does not automatically mean every app is exposed.

Use the VPN Leak Test in the affected browser, then repeat the check in another browser with the same VPN connection. The comparison helps you narrow down where the difference starts.

Test the browser with the VPN on

  1. Open the VPN Leak Test in the browser showing the warning. Keep the VPN connected while you test.
  2. Check how the VPN is running. A desktop VPN app may route traffic from the whole device. A browser VPN extension may protect only that browser, and its behavior can depend on the extension's settings.
  3. Run the test and note whether it reports a possible leak through IPv6 or WebRTC. If it shows an IP address, compare it with the VPN address shown in your VPN app, if available.
  4. Open the test in a second browser on the same device and network. Keep the VPN connected and note whether the result changes.
  5. If the VPN is a desktop app, repeat the test in a fresh browser profile with no extra extensions. If you use a VPN extension, make sure it is installed and enabled in the profile you test. Extensions are often off by default in private windows.

Write down which browser, profile, and VPN type you used. Changing several settings at once makes it harder to tell which change fixed the result.

What the result means

Only one browser reports the usual public IP

The affected browser may be exposing an address through WebRTC, using a different proxy, or not sending traffic through the VPN extension. This points toward a browser-specific setting or extension interaction, but check the VPN app's status before assuming the VPN itself is working everywhere.

Both browsers show the VPN address

The test did not find a public IP leak through the paths it checks in either browser. If a warning appeared earlier, repeat the test with extensions disabled one at a time. A different profile or a temporary network change may also explain the earlier result.

Both browsers show your usual public address

The issue may be broader than one browser. The VPN could be disconnected, configured for split tunneling, or not covering this type of traffic. Check the VPN app and its protection settings before using the connection for sensitive activity.

The result changes in a fresh profile

An extension, proxy setting, or profile-specific privacy option is a likely cause. Add extensions back one at a time and retest to identify the one that changes the result.

How to fix a leak in one browser

  1. Confirm what your VPN covers. Check whether you are using a device-wide VPN app or a browser extension. If it is an extension, confirm that it is connected in the affected browser and that its settings route the browser's traffic through the VPN.
  2. Reconnect the VPN and check its protection options. Disconnect and reconnect using the VPN app, then test again. If the app offers a kill switch or WebRTC protection, read its description and enable the relevant option. A kill switch is meant to block traffic if the VPN connection drops.
  3. Check for another proxy or VPN extension. Temporarily disable other VPN, proxy, privacy, or network-filtering extensions, then retest. On Windows 11, check Settings › Network & internet › Proxy for a manual proxy you did not intend to use. On macOS, check System Settings › Network › your active connection › Details › Proxies. VPN providers may also manage proxy settings in their own apps.
  4. Review the browser's WebRTC handling. Check the VPN provider's guidance for your browser and its WebRTC protection options. Avoid disabling WebRTC without understanding the tradeoff, because it can interfere with voice and video calls.
  5. Update the browser and VPN app. Install available updates, restart the browser, reconnect the VPN, and run the test again. An old extension can behave differently from a current desktop VPN app.
  6. Contact the VPN provider if the address still appears. Share the browser name, whether you use an app or extension, and whether the test identified IPv6 or WebRTC. Do not send passwords or account recovery codes.

What this test can and cannot show

The VPN Leak Test checks whether your real IP address appears through IPv6 or WebRTC while the VPN is on. A private local network address is different from your public IP address, so do not treat every address shown by a browser as proof that your ISP address has leaked.

A clean result is not a guarantee that every kind of traffic is protected. This test does not establish that DNS requests, apps outside the browser, or every connection type are covered. For more steps after a confirmed finding, see VPN leak detected? What to do next.

The test sends network requests to TooLab so it can check which IP address reaches the test. Keep the VPN connected during the check, and retest after changing one setting at a time.

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