MQTTClient Ipaddress defined is not referred in an assembly in xamarin forms

Hi,
i am started working on xamarin forms pcl mqtt concept with in that i cannot install M2MQTT 4.3.0 package, getting error. i have installed M2MQTT 4.2.0 with in that MqttClient() IPAddress defined is not referred in an assembly error is occurring. Please help me to fix it.