How to connect different device use Contiki UDP Sub-GHz

[PeterChen]

I have 1 Gateway and 2 devices(A and B).

I use example UDP-sender and UDP-receiver to try implement my project.

The gateway(Sender) with 2 devices(Receiver) communication is OK use Sub-Ghz.

But if my gateway first communicate device A then I change IP address and try communicate device B it's doesn't work, my device B can trigger interrupt but the unicast-receiver doesn't work.

Where am i wrong?

thanks everyone.​