I've got a AirPort Extreme Base station and several AirPort Express base stations. I can add the first AirPort Express without any issues its when I connect my 2nd AirPort Express station my entire internet gets disconnected. Not my AirPorts but my entire Comcast Xfinity connection gets disconnected. I don't think the actual internet is getting disconnected because all of the lights on the Xfinity modem are one and lit up. This tells me its still connected but the AirPort Base stations are getting disconnected. So here's what I'm trying to do if this will help answer some questions. I'm extending my network to the back of the house with one of the AirPort Express' and the other I'm using to connect my Sonos to be able to use AirPlay from my iPhone/iPad/etc. Any ideas as to what I'm doing wrong or if I can connect multiple AirPort Express' or what.