I wonder how much different it is from Wireguard + netcat. Both run encrypted channels over UDP, but somehow differently. What does QUIC offer that Wireguard does not?

QUIC includes a standard for peer address discovery: https://www.ietf.org/archive/id/draft-ietf-quic-address-disc...

Wireguard doesn't, which is why tailscale took off so much, since it offers basically that at its core (with a bunch of auxiliary features on top).

Show me some wireguard discovery/relay servers if I'm wrong.

Also, QUIC is more language-agnostic. The canonical user-space implementation of wireguard is in Go, which can't really do C FFI bindings, and the abstractions are about dealing with "wireguard devices", not "a single dump pipe", so wireguards userspace library also makes it surprisingly difficult to implement this simple thing without also bringing a ton of baggage (like tun devices, gateways, ip address management, etc) along for the ride.

If you already have a robust wireguard setup, then of course you don't need this and can just use socat or whatever.

They both run over UDP and always encrypt data. Beyond that superficial similarity they are completely different.

QUIC is a transport protocol that provides a stream abstraction (like TCP), with some improvements over TCP (like built-in support for multiplexing streams on the same connection, without head-of-line blocking issues).

Wireguard provides a network interface abstraction that acts as NIC. You can run TCP on top of a wireguard NIC (or QUIC for that matter).

Wireguard is a tunneling protocol. Netcat lets you write things over a socket. But netcat doesn't implement mechanisms for guaranteeing that all your packets arrive over UDP mode, so you're forced to tunnel TCP over UDP for reliability.

QUIC is all UDP, handling the encryption, resending lost packets, and reordering packets if they arrive out of order. The whole point of QUIC is to make it so you can get files transferred quickly.

WireGuard doesn't know the data you're sending, and netcat+TCP is stuck with the limitations of every packet needing to be sent and acknowledged sequentially.

Wireguard is opaque about the independent streams in its connection. So, while they both can encapsulate multiple concurrent streams in one connection, QUIC can do things like mitigate Head-of-Line Blocking and manage encryption at the transport layer. It also uses a connection ID on these substreams which helps make transitioning across network changes seamless.