Hi Roger,
Sorry you are having problems with this device. I don't know why the app is not receiving the broadcast message. I would only be able to investigate this if you could loan me the device so that I have hands-on access. If you would like me to do this, email me and I will send you my home address for you to post it to me.
The alternative is to manually configure the ip address of the PC into the BridgePal app. You can do this via the "Select BridgePal Server" menu function in the app. Select this entry from the menu and then tap on "<Add New Server>". Type in a server name (doesn't matter what name) and the PC's ip address, then tap on "Add". Your new entry should now be in the list that appears. Tap on the name and the app should now be able to communicate with the PC.
Ideally, you also need to fix the ip address of the PC, so that it doesn't change between sessions. Otherwise you will have to perform the above configuration each time that it changes. In most routers it's usually possible to reserve a static ip address for a particular device. This is done via the router configuration screens and the exact procedure will vary depending on the make/model of router. Alternatively, you can allocate a static ip address on the PC but this is less desirable if you may be using that PC on different networks from time to time.
John