Clients firewalls are outright configured to block UDP or not route UDP. This presents a problem to establish WebRTC sessions to our SipSorcery .NET backend, even when we provide a TURN server to proxy the traffic between peers. In this implementation, the browser is peer to the backend stack, the corresponding peer (on a static IP address)

While the client can establish a TCP connection to COTURN (our TURN server), it seems SipSorcery does not offer TCP options. It is not clear if this line L287 is a bug since "udp" is hard coded under the tcp condition: