title: Can a PINGREQ message be used by a gateway to update a network address in MQTTSN
body: <p>Im using an MQTTSN Gateway Version 1.2 from;</p>
  <p><a href="https://github.com/simon622/mqtt-sn" rel="nofollow noreferrer">https://github.com/simon622/mqtt-sn</a></p>
  <p>I notice that a when a client connection goes to sleep and then subsequently wakes up, its IP address may well have changed on the network. When the next PINGREQ message is sent by a client, the gateway is unable to establish its identity from the network address and so the session simply times out.</p>
  <p>Is there anyway of updating the network address in this scenario to tie it back to the original session without having the overhead of a new CONNECT?</p>
  <p>I tried issuing a new PINGREQ, but the gateway was unable to link the new network address to an existing gateway session.</p>