Mirror is a high level Networking Library that can use several different low level transports. To use a transport, simply add it as component to the NetworkManager and drag it into the NetworkManager's Transport field.
kcp2k - KCP Transport based on kcp.c, line-by-line translation to C#
Latency Simulation Transport to test non-ideal network conditions
libuv2k - TCP Transport - based on Native C networking backend used by Node.js.
Telepathy - TCP Transport - Simple, message based, MMO Scale TCP networking in C#. And no magic.
WebSockets - WebSockets transport layer for Mirror that target WebGL clients.
Multiplexer Multiplexer is a bridging transport to allow a server to handle clients on different transports concurrently, for example desktop clients using Telepathy together with WebGL clients using Websockets.
Fallback Fallback is a compatibility transport for transports that don't run on all platforms and need fallback options to cover all other platforms.
UDP - Ignorance Ignorance implements a reliable and unreliable sequenced UDP transport based on ENet.
Steam - FizzySteamworks Transport utilising Steam P2P network, building on Steamworks.NET.
Steam - FizzyFacepunch Transport utilising Steam P2P network, building on Facepunch.Steamworks.