[philipgm]

The PC is on this 192.168.1 network too?

Yep, same network.
I notice on Line 603 to 605 of the Net.ino file of the RX_v2.1_b001 firmware there is this:-

 void handleNotFound(){
    server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the request
  }

I seem to be getting that far as I see that "404: Not found" message.
No idea what handleNotFound means though. 
Hmmmm !