Fedora 23 KDE spin

XEN-4.5.2 and kernel 4.2.8 booted via EFI where everything works fine using virt-manager to manage vms under XEN, all is good.

a recent update installed kernel-4.3.3 so i reset the xen efi configuration, booted got into the desktop no problems. The issue arises when trying to launch vms from virt-manager, it always throws a  virt-manager viewer connection to hypervisor host got refused or disconnected.

however, if i go back to using kernel 4.2.8 it all works fine. So there in lies the question, whats changed that is now preventing virt-manager from aunching vms properly.

Sorry for the cross post, just trying to find the answer. thanks in advance