Packet loss on MUC

I set an Openfire on windows server 2012 R2 and it seem to be working on HTTP bing.

Then i set up conversejs as an xmpp client for MUC chat.

The problem is messages are not always reaching destinations, there is a packet loss.

In the server warning i’m always getting this error

2015.10.09 11:11:21 org.jivesoftware.openfire.http.HttpSession - Unable to deliver a stanza (it is being queued instead), although there are available connections! RID / Connection processing is out of sync!

How can i solve it? i did not find any questions about this