I'm just starting trying to use Xamarin.iOS, building in Visual Studio with a build host of a brand new Mac Mini.
Various bits of version information:
(I've tried various different versions, which behave in the same way.)
Xamarin Business Licence (.iOS, .Mac, .Android) - activated in the normal way on Windows, but out of desperation I've activated it manually on the Mac (by downloading the licence file).
Both machines are connected via ethernet on the same local network. The Mac has no firewall on (which is alarming in itself, to be honest). Windows just has the normal firewall configuration - nothing out of the ordinary.
I've managed to start Xamarin Studio on the Mac Mini, and debug the master/detail demo on the iPad simulator. The problems come when I try to use it as a Build Host from the PC.
In Visual Studio, under Options / Xamarin / iOS Settings, Current Mac Build Host, Configure, the dialog does see my Mac - but it has problems communicating with it. In the list, it either shows it as Unreachable, or Not Activated. When I click on Diagnose, it's fine until the "Establishing a stateful connection to Mac build host via HTTP" - that usually works (but not always), but takes a long time - a suspiciously long time. The "Comparing Remote and Local MonoTouch SDK" part always fails, but I've never been prompted to update either system to get them in sync.
The activation part usually comes up green now, but until I manually activated it, I could hit the "Activate" button as many times as I wanted, but I only saw "Unable to connect to the remote server" - which is also what I get when trying to launch an application.
It definitely sounds like a network issue somewhere, but I can't tell where - especially as it sometimes seems to get through. Any further diagnostics I should try to perform?