Just incase someone searched for this issue, the reason that you are getting "failed to connect to IP Office" even though you may be in the same subnet w/ firewalls off etc, is because of the amount of traffic like kyle1532 was suggesting.
In my case, I had one-X portal installed, which seemed to be taking up a ton of connections on that local host. Perform a netstat from the command line to see how many, if it begins to scroll endlessly off the screen that is most likly the case.
I uninstalled One-X portal and was able to connect right away, and my netstat showed very minimal traffic, which would appear normal.
Now, the question is, why would One-X Portal be causing so much traffic? Perhaps it would be best to keep it on a seperate server.