Asmack4.0.5 How to deal with Muc after Connection reConnect

How to deal with Muc after Connection reConnect ?

when i switch wifi on/off Xmpp connection can reConnect and connect Success ( i already add ConnectionListener )

but how can i reset muc and let me can send message …

I try to join room again and success but no longer i can not send message… i dont know why…

plz help me solve this …Tks

Sorry for my English…

upd:

when i can not send message 5 min later i get reconnectionSuccessful() from ConnectionListener call back

i got this exception : Connection closed with error java.net.SocketException: recvfrom failed: ETIMEDOUT (Connection timed out)