We can't set the Flow with the Unifying. This is something that bothered me a lot, because when I have to use VPN or other secure connection in one laptop, the Flow doesn't work so well, and this was a test that I did between Macs and Windows. When I needed to use Flow with Mac and Windows on the same network, they couldn't found each other (with VPN enabled or not). But another Mac without secure connection enabled, could find my Windows computer. Which became a huge problem, because if I have the 3 machines on, the Macs can communicate (no very well, but they can) and the second mac (not with VPN) goes crazy and doesn't know which device to connect (First mac or Windows).
IMPORTANT: All machines are connected to the same network and all of them are in Wi-fi mode.