Understanding VPN Protocols: WireGuard, OpenVPN, and IKEv2 Explained

If you have ever opened your VPN app and noticed a setting labelled "Protocol" with options like WireGuard, OpenVPN, and IKEv2, you might have wondered what these terms mean and whether it matters which one you choose. The short answer is that it does matter — your choice of protocol affects your connection speed, security, and reliability. The good news is that understanding the basics is easier than you might think.

In this article, we explain the three most common VPN protocols in plain English, compare their strengths and weaknesses, and recommend which one UK users should choose for different use cases. If you are still selecting a VPN provider, visit our free VPN comparison tool to see which protocols each service supports.

What Is a VPN Protocol?

A VPN protocol is the set of rules that governs how data is transmitted between your device and the VPN server. Think of it as the language your device and the server use to communicate. The protocol determines how the encrypted tunnel is established, how your data is packaged and encrypted, how the connection is maintained, and how errors are handled.

Different protocols make different trade-offs between speed, security, and compatibility. Some prioritise raw performance, others focus on maximum security, and some aim for the best balance of both. Most modern VPN apps let you choose which protocol to use, though many also offer an "Automatic" option that selects the best protocol for your current situation.

WireGuard: The Modern Standard

WireGuard is the newest of the three protocols we are discussing, and it has rapidly become the industry standard. Released as a stable version in 2020, it was designed from the ground up to be simpler, faster, and more secure than its predecessors. The entire WireGuard codebase consists of approximately 4,000 lines of code, compared to over 400,000 lines for OpenVPN. This smaller codebase makes it easier to audit for security vulnerabilities and significantly less likely to contain bugs.

In terms of performance, WireGuard is the clear leader. In our UK speed tests, WireGuard connections are consistently 30 to 50 per cent faster than OpenVPN and 10 to 20 per cent faster than IKEv2. Latency is also lower, making WireGuard the best choice for latency-sensitive activities like gaming and video calls. The protocol uses state-of-the-art cryptographic primitives including ChaCha20 for encryption, Poly1305 for authentication, and Curve25519 for key exchange.

WireGuard's main limitation is that it was originally designed to assign each user a static IP address, which could theoretically be used to identify users. VPN providers have addressed this with their own implementations — NordVPN's NordLynx wraps WireGuard in a double NAT system to ensure no identifiable data is stored, while other providers have developed similar solutions. These implementations mean that in practice, WireGuard is just as private as any other protocol when used through a reputable VPN provider.

Most major VPN providers now support WireGuard. NordVPN uses it as the basis for NordLynx, Surfshark and CyberGhost offer it as a selectable option, and Mullvad VPN was one of the earliest adopters. Private Internet Access also enables WireGuard by default on all its apps.

OpenVPN: The Proven Veteran

OpenVPN has been the gold standard of VPN protocols for nearly two decades. First released in 2001, it is open-source software that has been extensively audited and battle-tested over more than twenty years of real-world use. Its security credentials are impeccable — no critical vulnerabilities have been discovered in the core protocol in recent years, and its use of the OpenSSL library gives it access to a vast range of cryptographic algorithms.

OpenVPN supports two modes of operation: UDP and TCP. UDP is faster and is the default for most VPN applications. TCP is slower but more reliable, and it can be configured to run on port 443 — the same port used by HTTPS web traffic — making it extremely difficult for networks to block. This makes OpenVPN TCP an excellent choice for users in restrictive environments where VPN traffic is actively filtered, such as certain corporate networks or countries with internet censorship.

The downside of OpenVPN is performance. Its large, complex codebase and reliance on the TLS handshake process mean that it is significantly slower than WireGuard. Connection times are longer, and throughput is lower, particularly on mobile devices where the processing overhead is more noticeable. For most UK users with fast broadband connections, the speed difference is tolerable but noticeable — expect to lose an additional 15 to 25 per cent of speed compared to WireGuard.

Despite its age, OpenVPN remains an excellent choice for users who prioritise proven security and maximum compatibility above all else. Virtually every VPN provider supports it, and it works on almost every operating system and device imaginable.

IKEv2: The Mobile Favourite

Internet Key Exchange version 2, paired with the IPsec protocol suite, is a protocol developed jointly by Microsoft and Cisco. It offers a strong balance of speed and security, with performance that sits between WireGuard and OpenVPN in most tests.

Where IKEv2 truly shines is on mobile devices. It supports the MOBIKE (Mobility and Multihoming) protocol, which allows it to seamlessly switch between network connections without dropping the VPN. If you walk from your home Wi-Fi to your mobile data connection, IKEv2 will automatically re-establish the VPN tunnel in a fraction of a second. This makes it an excellent choice for smartphone users who are constantly moving between networks.

IKEv2 is also fast to establish initial connections. The handshake process is quicker than OpenVPN, meaning you spend less time waiting for the VPN to connect. Security is robust, using AES-256 encryption by default along with strong key exchange mechanisms.

The main drawback of IKEv2 is that it is not open-source in its original implementation, though open-source versions like strongSwan do exist. It can also be easier to block than OpenVPN because it uses fixed ports that are easy to identify. For users on unrestricted UK broadband connections, this is rarely an issue, but it is worth noting for those who might need to use a VPN on restrictive networks.

Providers like ExpressVPN, NordVPN, and IPVanish all offer IKEv2 as a protocol option, and it is often the default on iOS devices due to its strong integration with Apple's networking stack.

Which Protocol Should You Use?

For most UK users, we recommend WireGuard as your default protocol. It offers the best speeds, lowest latency, strong security, and is supported by virtually every major provider. If your VPN app has an "Automatic" setting, it will typically select WireGuard or a WireGuard-based protocol like NordLynx or Lightway.

Switch to OpenVPN TCP if you are on a network that blocks VPN connections, as its ability to run on port 443 makes it very difficult to detect and filter. Use IKEv2 on your smartphone if you find that your VPN frequently disconnects when switching between Wi-Fi and mobile data.

Whichever protocol you choose, make sure you are using a reputable VPN provider with a verified no-logs policy and strong encryption standards. Visit BestVPN UK for our latest provider reviews, or use our free VPN comparison tool to compare options side by side.