I have just bought a new airport express base station to add on to existing Cisco fibre router as old TP Link range extenders were rubbish and this airport is just as bad I'm afraid to say ! :-( I have wired my own ethernet sockets in every room and am a self employed Electrician, data wiring tech and fibre and copper comms installation / fault teacher / senior engineer. So it's been wired correctly to the ethernet port but everytime it's linked and on green it causes mayhem and stops the wifi working let alone boosting it ! what is the problem as many seem to have these issues and nothing works until it's powered down and removed from the network router etc... ?