I believe that means that the Network TCP IP Communication Test Failed. This is for the network card, not the modem. Do you see any other messages when you look at the detailed test log?
You could also check that the cable is properly plugged in and that the connection is configured properly. If it's not on a network it won't run properly. Also if you have a software firewall on your PC you might have to configure it to allow the test to run, or disable it while testing.
Good luck!
