Different browsers problems

I have migrated a chat from a dedicated debian server to a new CLOUD server. Everything is ok, after [login to view URL] Last problem:: messages sent by an user to a second opponent user arrives correctly, the answer of the second to the first, as well. Now: it works PERFECTLY only between Safari user to Chrome user and vice-versa. With Internet explorer it does not work. With other combination like Firefox/Chrome it works one way but not for the answer. My GUEST: this is a problem of settings for the different browsers. But I do not know: which software: Stomp?ActiveMQ?Orbited?PhP? If you know the answer , you should fix the problem in less that one hour. Just answer if you know how to fix browsers issues.