Well, first, "will not work" isn't very descriptive of what happens, nor of what you want to happen (which isn't at all clear from your message). Second, as has been posted here innumerable times, all issues with the 6.0 beta should be sent to smebugs@mitel.com.
I'd suggest, if you contact them, that you explain what the "3rd IP" and "4th IP" are, what behavior you're expecting, and what you're observing.