I have had sporadic issues with the app not allowing me in. It just tells me, "We need an Internet connection." I certainly have an internet connection. It has been this way for a few days, and it has worked for me recently. Nothing has changed with my network.
It sounds like you are out of range of the gateway's wi-fi signal?
If you are using an Android device to access to xFi app, please try going into Settings and clearing out the App Cache and App Data for xFi. There was a setting introduced in v1.6 of the app that was causing the message to pop errantly; it has since been reverted.
If this does not work or you are receiving this message with an Apple device, please send me a Private Message.