I have successfully used v 0.32 in a deployment setting (Windows DHCP/HyperV/etc.) without major issues. I have just setup v 1.2.0 on an Ubuntu Server v 14.04.1 x86 install (VirtualBox) but I can not PXE boot a client when connecting via a managed network switch. If I use a crossover cable, no problem at all, I am able to load the FOG boot menu and proceed with pending tasks, etc. Mind you, simple setup in an isolated network, letting FOG handle DHCP, etc.
Also experienced the same problem when running on an enterprise network in VMWare. Granted, this secondary setup involved Windows DHCP and VLANs across Cisco switches, I expected the installation process not to roll out quite as nicely. Still, though, I can not figure out why I am successful over a crossover cable but not so when using an intermediary switch.