Networking example projects won't connect

Neither the official networking demo nor the M2H networking demo work for me--I have not been able to connect to myself, the attempt times out every time with no mention of a client on the server instance. I have tried it with a lot of different setups including:

• On a mac connecting a webplayer client to the editor server and vice versa
• Same, on a PC
• Connecting my mac to my PC over an internal network
• Various attempts with standalone executables

The firewall on my mac is off and I'm fairly certain I have the exception for port 25001 set up correctly on my PC.