I've heard people say that a hub (NOT a switch) is required when bridging more than one client (likely due to the fact that a switch doesn't let the bridge see all the traffic from the clients). But I don't think this matters.
Also, `parprouted` has a bug where it prints its log messages as raw Ethernet frames over the network. If something isn't working, open Wireshark and restart `parprouted`. Look for white "Ethernet II" frames.