Upgrade the latest firmware, http://www.tp-link.com/en/download/TD-W8980_V1.html#Firmware Disable UPnP for a try.

If you hard reset it, any changes of those lights? If not, it may be faulty. Under warranty, try to get a replacement.

What's the distance between your extender and main router? How many signal lights on WA750RE? If less than 3, maybe you should move the extender closer to the router.

When connection drops, powerline lights on two units in TL-WPA4230P KIT go off and you have pair them, right? Are they both plugged in wall sockets directly? Read this article to get some hints....

Hi Ben, you can pair two powerline adapters and the network will be private and secured. No worries. http://www.tp-link.com/en/faq-258.html

Power light on WPA4220 is on? If you press Wi-Fi clone button for 5 seconds to enable the wireless function, the Wi-Fi light will be flashing or not? If nothing change, it should be faulty. Under...