This video shows how to setup LumaShare for offline QR Code sharing. This can be used when no internet service is available. You will still need a wifi router to connect the devices and allow guests to join the network for file sharing. This is a great option when internet connections are slow or not available.
Trouble shooting note: If you started LumaShare while connected to one network, then change to a private network, you may need to restart LumaShare so that it is using the correct IP Address for local sharing.