ScienceBoy
Money List Winner
I got the TP link type and they worked fine for a couple of months but then suddenly stopped working, I've tried resetting, pairing and set up again but no joy. sad.
Ours did the same after about 2 years, the box at the router end had gone inside. Good old John Lewis to the rescue, they will replace anything as long as you have a receipt and a good reason. Best customer service I know!
If you can work out which one is broken you might be able to replace it from eBay or return it if you have the reciept.