I have this problem as well. Put the EE device in the front window connected by ethernet cable to the BT Smart Hub. Flashing red bars. Haven't bothered to contact BT as they obviously don't know what's causing it, according to previous posts. I've disconnected the device until BT and EE find a fix. If my broadband goes down I'll use a hotspot provided by my mobile operator until it comes back. On the bright side, the extender is working well and that was the main reason I upgraded to the Smart Hub.
