A protocol is the set of rules by which an app and a server agree on a connection and transfer data. The choice of protocol affects speed, stability, and how noticeable the connection is from the outside. Let's look at the ones you actually come across.
Short answer
Protocols roughly fall into two groups. The first was built for reliability and speed — OpenVPN, WireGuard, IKEv2. The second appeared later and solves a different task: making the connection indistinguishable from ordinary web traffic — VLESS Reality, Trojan, Hysteria 2. These aren't "old and new," they're different goals.
Classic protocols
OpenVPN
It appeared in 2001 and became the industry standard. Open source, decades of audits, runs over UDP or TCP. Its main drawbacks are its bulky code and an easily recognizable traffic profile: where connections are filtered by type, OpenVPN stands out.
WireGuard
A modern replacement: around four thousand lines of code versus hundreds of thousands in OpenVPN, fast connection setup, good speed. It runs over UDP only. Masking wasn't one of its goals — its traffic is recognizable too.
IKEv2/IPsec
Built into Windows, macOS, and iOS, so it works without a third-party app. It handles network changes well — for example, switching from Wi-Fi to mobile data. It uses fixed ports, which makes it vulnerable to simple port-based blocking.
Protocols designed for filtering
VLESS Reality
The VLESS transport with the Reality layer on top: the connection looks like a request to a real public website, and when probed from outside, the server returns that site's genuine response. A detailed breakdown is in a separate article.
Trojan
It disguises the tunnel as ordinary HTTPS. If a request arrives on the port without the correct password, the server behaves like a regular web server. Simpler than Reality in design and reliable where filtering isn't too deep.
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Hysteria 2
Built on top of QUIC and optimized for networks with packet loss — mobile data, congested channels, long routes. Where TCP protocols degrade due to retransmissions, Hysteria holds its speed noticeably better.
Comparison
| Protocol | Strength | Weak point |
|---|---|---|
| OpenVPN | Time-tested, open source | Heavy, easily recognized |
| WireGuard | Speed, simplicity, little code | Recognizable, UDP only |
| IKEv2 | Built into the system, survives network changes | Fixed ports |
| VLESS Reality | Indistinguishable from visiting a website | Harder to set up, higher overhead |
| Trojan | Simple and reliable HTTPS masking | TCP only |
| Hysteria 2 | Resistant to packet loss | Requires UDP, which is sometimes throttled |
Which protocol is "the best"
There's no such thing. On a stable home network, WireGuard will be the fastest. On a network where connections are filtered, it may not come up at all, while Reality or Trojan will. On mobile data with packet loss, Hysteria 2 wins. The question isn't about a ranking, but about fitting the conditions.
How it works at VolnaLink
We use VLESS Reality, Trojan, and Hysteria 2. There's no protocol switch in the app: the client picks the suitable one itself, based on the network. This is a deliberate decision — choosing manually requires understanding what's happening on a specific network right now, and the user usually doesn't have that information.
The practical takeaway: if the connection won't establish, what you need to change is the location, not the protocol.