My previous setup, all working fine:
BT Hub >WiFi> BT WiFi Extender Disc >ethernet> AV600 powerline ethernet #1 >mainspower> AV600 powerline ethernet #2 >ethernet> laptop.

My new attempted setup to give me WiFi in my office as well as ethernet:
BT Hub >WiFi> BT WiFi Extender Disc >ethernet> AV600 powerline ethernet #1 >mainspower> AV600 powerline Wifi Extender >ethernet + WiFi> laptop+mobiles

However the BT system doesn't seem to like the WiFi Extender AV600. The BT WiFi extender gives me an angry red error light whenever I try to pair the new AV600.

Any ideas what the issue is here and how to fix if possible?