Avoid MediaRelay's channel to continously swap between IPv6 and IPv4 during ICE connectivity checks. Indeed, this causes some connectivity checks to fail because some stun requests sent over IPv6 are answered over IPv4 and vice versa. The workaround implemented consists in locking the destination choosen by the MediaRelay's channels (when receiving a packet) for a minimum of 5 seconds. The switch to a new destination is allowed only if the previous destination has been unused over the last 5 seconds.