There is not even a connection. During the RTCPeerConnection's "ICE Gathering" process local IPs are discovered and, if STUN/TURN servers are configured within

There is not even a connection. During the RTCPeerConnection's "ICE Gathering" process local IPs are discovered and, if STUN/TURN servers are configured within the RTCPeerConnection, STUN requests are sent to those servers (which help retrieving the public IP of the computer/router). But you don't need even to send a single packet in order to get local IPs (private ones, VPN ones, etc).