Thank you Peter. I was afraid that would be the answer. I'll work my way round the house. Stella Qin from TPLink Support suggested having the following which is proving very useful so Thanks Stella...

Model : Hardware Version : Firmware Version : ISP : My PA4010+ 2xAV500 set up has worked well for a year or three but recently failed. Both AV500s have no powerline indicated. Moving an AV500 very...