TURN is the solution for communicating around Symmetric NAT. STUN is used to determine the type of NAT a user has, which helps determines the connectivity meth

TURN is the solution for communicating around Symmetric NAT. STUN is used to determine the type of NAT a user has, which helps determines the connectivity method to use between endpoints. Connectivity can be direct to each other or must routed through a TURN server. IPv6 still uses NAT and Firewalls, which is a pain, but it is a reliable method of defense. Almost all Cellular Networks are on Symmetric NAT, so P2P games are always going to require a TURN server. However, almost all WiFi networks use Port Restricted NAT (a level below symmetric), or lower, which is still possible to make direct p2p connections. (I am working on my own Networking/P2P library for Unity, which is a painful process.)