If I understand correctly, most QUIC implementations of clients and servers uses unconnected UDP sockets with sendto()/sendmsg() and recvfrom()/recvmsg(). For the server side, this is probably because they adopt event-driven programming. The event loop calls recvfrom()/recvmsg() and dispatches a received packet according to the peer address. As I explained in "Implementation status of QUIC in Hask