There’s a funny little contradiction with VPNs.
You can open an app, tap “Connect,” see the reassuring VPN icon and feel like you’ve locked everything down. Then you open a browser and discover that there are other ways your real IP address can potentially slip through.
Have you ever wondered why privacy guides keep mentioning WebRTC, IPv6 and leak tests?
They’re not just trying to make VPNs sound complicated.
Your IP address can reveal useful information about your connection, including an approximate location and the network you’re using. A VPN is supposed to replace that visible address with the VPN’s address, but certain browser and network features can complicate things.
Mysterium VPN reviewers have an article that goes more in depth into testing VPN connections and spotting IP leaks, including WebRTC and IPv6 checks.
Your Browser Has a Few Tricks of Its Own
Most people think of a browser as the thing that displays websites.
Fair enough.
But modern browsers do plenty behind the scenes, and WebRTC is one example.
WebRTC allows browsers and devices to establish direct connections for things such as video calls, voice communication and real-time sharing. The useful part is that these direct connections can sometimes reveal an IP address even while a VPN is active.
Mysterium’s help center explains that a WebRTC leak can reveal your real IP address and potentially indicate your approximate location, although it doesn’t expose your browsing history or activity by itself.
That’s why ip leak protection isn’t something I’d ignore when choosing a VPN.
So, What Does an IP Leak Actually Mean?
Let’s keep this simple.
Your VPN gives websites a VPN-associated IP address instead of your normal public IP.
An IP leak means your actual address becomes visible through a connection that wasn’t properly routed through the VPN.
It’s not necessarily a catastrophic privacy failure.
But it’s still a gap.
Imagine wearing a raincoat while walking through a downpour, except there’s a tiny hole in the sleeve. You’re still mostly protected, but that doesn’t mean you’d ignore the hole.
The same idea applies here.
A VPN can provide encryption and hide your normal IP in most situations while another feature, such as WebRTC or IPv6, creates an unexpected route.
Why WebRTC Is Worth Checking
WebRTC is particularly interesting because it lives inside the browser.
You might never install anything related to it. You may not even know it’s there.
Yet websites can use WebRTC functionality to establish direct connections.
On Chrome and Edge, Mysterium’s guidance says there aren’t built-in controls specifically for disabling WebRTC, while Brave and Opera provide a setting related to non-proxied UDP. Firefox users can change a WebRTC preference through its advanced settings.
The exact settings can change as browsers evolve, so don’t treat an old screenshot from a random forum as gospel.
That’s one reason testing is more useful than guessing.
What About IPv6?
Here’s another piece of the puzzle.
Your phone or laptop may support IPv6 without you ever consciously enabling it. It’s simply part of how modern networks can connect devices to the internet.
If a VPN doesn’t properly account for IPv6 traffic, your real network address could potentially be exposed outside the VPN route.
Mysterium’s current help center specifically has troubleshooting guidance for IPv6 and DNS-related leaks, including advice to check IPv6 configuration when investigating privacy problems.
This is particularly relevant on newer smartphones and home networks where IPv6 may already be available.
So if you run an IP test and everything looks fine, but you’re being especially careful about privacy, checking IPv6 is worth adding to the list.
How Do You Know If You’re Leaking?
This is the nice part.
You don’t have to stare at network settings until your eyes go square.
Test it.
Before connecting your VPN, check your normal public IP address.
Then connect to Mysterium and check again.
Your visible IP should change to the VPN connection’s address.
Mysterium’s own guidance recommends checking your IP to verify a successful VPN connection, and its current features page lists IP leak protection as one of the service’s privacy features.
For a more complete check, you can also use browser-based leak testing tools that examine IP, DNS and WebRTC behavior.
And don’t just test once.
Try it on Wi-Fi.
Then try mobile data.
If you’re really curious, switch between them while connected and test again.
Why? Because smartphones love changing networks when you aren’t looking.
The Coffee Shop Test
Let’s make this practical.
You’re sitting in a café with a phone, a half-finished cappuccino and Wi-Fi that keeps flickering between “excellent” and “why is this taking thirty seconds?”
You connect your VPN.
Everything seems fine.
Now imagine the Wi-Fi connection drops and your phone switches to mobile data.
That’s completely normal smartphone behavior.
But it’s also the sort of situation where connection settings can change quickly.
Mysterium recommends testing different networks when troubleshooting connection problems, and its mobile guidance discusses issues that can arise from background restrictions and battery-saving settings on phones.
If something seems strange after a network switch, reconnecting the VPN and running another leak test is a much better response than simply assuming the VPN is still behaving exactly as before.
Does a VPN Need More Than IP Protection?
Absolutely.
An IP address is only one piece of the privacy puzzle.
DNS requests are another.
WebRTC can be another consideration.
And then there’s the VPN connection itself.
That’s why a good privacy setup tends to use several safeguards rather than relying on one feature.
Mysterium currently lists IP leak protection alongside DNS leak protection, a kill switch, WireGuard and a no-logs policy. Its mobile and desktop apps also support residential IP connections and multiple device coverage.
Each feature tackles a slightly different problem.
That’s useful because internet connections aren’t exactly famous for being predictable.
What If a Website Still Sees the Wrong Location?
This can happen, and it doesn’t automatically prove that your IP is leaking.
Websites use databases to estimate where IP addresses are located. Those databases aren’t always perfect.
Mysterium notes that some websites can report outdated or incorrect information about residential IP locations, particularly when their databases haven’t caught up with newer addresses.
So if a website says you’re in a neighboring city when you’ve selected another location, don’t immediately panic.
Try another IP.
Mysterium provides a refresh option for changing the current VPN IP, although its documentation says temporary limits can apply to frequent refresh requests.
A Simple Leak-Testing Routine
You don’t need to turn privacy testing into a hobby.
A basic routine is enough:
Connect the VPN and check your public IP.
Run a DNS leak test.
Check WebRTC behavior in your browser.
Consider IPv6 if you’re using a modern network.
Repeat after major browser, operating-system or VPN changes.
And test both Wi-Fi and mobile data if you’re mainly using a smartphone.
It takes a few minutes.
That’s a pretty good trade for knowing whether the privacy settings you’ve chosen are actually behaving as expected.
The Real Lesson About VPN Privacy
The biggest mistake is thinking a VPN is simply an on/off switch.
It’s more like a collection of small systems working together.
Encryption protects the connection.
IP leak protection helps prevent your real IP from escaping.
DNS leak protection keeps DNS requests inside the VPN tunnel.
A kill switch can stop traffic if the VPN suddenly disconnects.
WebRTC and IPv6 deserve attention because they can behave differently from the ordinary traffic people usually think about.
Mysterium’s current feature set brings several of these protections together in its apps, including IP leak protection, DNS leak protection and a kill switch.
One Last Check Before You Forget
If you’ve had a VPN installed on your phone for months and never tested it, this is a good excuse.
Grab your phone.
Connect to the VPN.
Check your IP.
Run a DNS test.
Look at WebRTC.
Think about IPv6.
Then switch from Wi-Fi to mobile data and check again.
You might find everything is working exactly as it should.
That’s the ideal outcome.
And if something does look unusual, you’ve found it before assuming that little VPN icon was telling you the complete story.
Because when it comes to online privacy, the boring five-minute check is often more valuable than the fanciest feature list.