We have one or two TP link range extenders, because it is quite a long house, and the WiFi signal is almost non-existant at the ends of the house without them. Over the weekend, one extender was no longer detected by our devices, and the bottom WiFi green light was no longer on. We unplugged it, re-booted the devices, re-set the extender all to no avail. Cannot think what has changed, but nothing seems to be rectifying it. The two upper lights are on when it is plugged in.