A VPN, or Virtual Private Network, creates an encrypted tunnel between a device and a remote server. Internet traffic passes through this tunnel, which masks the user’s real IP address and makes the data unreadable to anyone trying to intercept it. This technical definition sets the framework, but the practical use of a VPN for online privacy requires understanding what it actually protects, and especially what it does not protect.
QUIC Leaks and Mobile Traffic: The Blind Spots of a VPN
Activating a VPN is not enough to ensure that all traffic goes through the encrypted tunnel. Independent audits conducted in 2024-2025 revealed that some VPN clients poorly manage the HTTP/3 and QUIC protocol, used by Google, YouTube, or Facebook. Part of the traffic may then exit the tunnel in clear text, exposing metadata or even content.
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Split tunneling, which allows users to choose which applications go through the VPN, exacerbates the problem when misconfigured. QUIC traffic then escapes encryption without the user’s knowledge.
On mobile, the situation becomes more complicated. Since 2024, Apple (iOS 17) and Google (Android 14) have tightened their rules regarding VPN applications in their stores. So-called “filtering” VPNs, which block ads and trackers by inspecting traffic, are subject to restrictions.
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Some VPN applications integrate advertising SDKs themselves, which amounts to replacing one tracking method with another. Checking the permissions requested by the application and its data collection policy remains a step that most users overlook.
A VPN configured on a traditional desktop client generally offers finer control over these settings than a mobile app downloaded from a store. This is a point to keep in mind when looking to protect your online privacy via a smartphone.
VPN Encryption and Protocols: What Matters for Privacy
Encryption is the technical foundation of a VPN. Not all providers use the same protocols, and the choice of protocol directly influences the level of protection.
- WireGuard has become the reference protocol for the majority of consumer providers. Lightweight and fast, it uses modern cryptography, and its reduced code facilitates security audits.
- OpenVPN remains widely deployed, particularly on manual configurations (routers, NAS). Its age is both an asset (code audited for a long time) and a limitation (lower performance than WireGuard on fast connections).
- IKEv2/IPsec offers quick reconnection during network changes, making it suitable for mobile devices switching from Wi-Fi to 4G/5G.
The protocol alone does not do everything. A provider that logs connections (timestamps, source IP, data volume) can technically reconstruct part of the activity, even if the content remains encrypted. The no-logging policy should ideally be verified by a published independent audit. Several providers like NordVPN, Surfshark, or ExpressVPN have undergone this type of audit, but the frequency and scope vary.
Configuring a VPN for Real Daily Protection
Installing a VPN application takes a few minutes. Configuring it to actually protect privacy requires a bit more attention.
Activate the Kill Switch
The kill switch automatically cuts off the internet connection if the VPN tunnel drops. Without this function activated, a temporary disconnection from the VPN server exposes traffic in clear text for a few seconds, sometimes long enough for an ISP to log a DNS request or for a site to identify the real IP address.
Disable QUIC Traffic in the Browser
To avoid leaks related to the QUIC protocol, a simple action is to disable this protocol in the advanced settings of the browser. On Chrome, the page chrome://flags allows you to force the classic HTTP/2 protocol, which passes correctly through the VPN tunnel.
Check for DNS Leaks
A DNS leak occurs when domain name resolution requests go through the ISP’s DNS server instead of the VPN’s. Online tools allow you to test if the VPN properly handles DNS requests. A VPN that leaks DNS exposes visited sites even if the content of the pages remains encrypted.
Free vs Paid VPN: The Trade-offs on Privacy
Free VPNs fund their infrastructure through means other than subscriptions. Integrated ads, resale of aggregated browsing data, or shared bandwidth with other users are part of documented business models.
A paid provider like CyberGhost, NordVPN, or Proton VPN generally offers a more extensive network of servers (covering several dozen countries), higher speeds, and a stricter privacy policy. The monthly cost decreases significantly with a two-year commitment.
Some providers offer a limited free version, like Proton VPN, which restricts the number of servers and speed without monetizing data. This type of offer constitutes an acceptable compromise for testing the service before committing.
What a VPN Does Not Protect
A VPN masks the IP address and encrypts traffic between the device and the VPN server. It does not protect against tracking by cookies, browser fingerprinting, or against data voluntarily shared with a connected service.
Logging into a Google or Facebook account with an active VPN does not prevent these platforms from associating activity with the user profile. The VPN operates at the network layer, not the application layer. Combining a VPN with a hardened browser and a tracker blocker remains the most effective combination to limit online tracking.
Private browsing in the browser does not serve the same role either: it prevents local storage of history and cookies but does not mask anything at the network level. These two tools complement each other without substituting for one another.