I was at a client's house, trying to set up wifi and Airport Expresses with xfinity. After unplugging and resetting the modem several times, ensuring I had restarted devices in order and seeing 2 green lights in the Airport Utility, I found out it was only set up for wired, not wireless. Then, I saw options: "Create a wireless network" or "Extend a wireless network". Another 1/2 hour goes by. Couldn't get either to work. Having trouble getting online wirelessly through the AirPort Extreme by itself. Could not get the Airport Expresses to work either. This is his setup: Xfinity internet Motorola SURFboard SB6120 router (What looks like) an Apple Mac Pro ‑ Xeon (has 2 ethernet ports in the back - one plugged directly into the AirPort Extreme) AirPort Extreme Base Station A1521 2 Apple Airport Expresses A1264 [ an older Time Capsule (1 or 2 TB), not being used ] It's a 2 story house. He has network wiring in the walls and outlets upstairs. Mac is running Yosemite, all updates ran, he was advised by a local shop not to upgrade to El Capitan just yet. As mentioned above, I was able to get online with the modem directly and through the AirPort Extreme, that's about it. If I recall correctly, I found the modem IP to be 188.8.131.52, however, after entering in the address bar of a browser, as I've done before, it did not resolve. I could ping it, but did not get the login screen. I followed https://customer.xfinity.com/help-and-support/internet/set-up-xfinity-internet-on-mac-os-x/. I don't recall a Show menu. I recall "Configure IPv4 menu, select Using DHCP.". I think I did do that. Pretty sure PPPoE was not selected. Called Comcast around 7 times. Always got a busy. He is using a neighbor's wifi, and his network is not showing, so 'wifi connected' isn't really true. It's not connecting to his own network. Here are images of the screens and the Mac. http://postimg.org/gallery/16rmy1c5e/ I go back tomorrow to revisit. Can someone advise what to do?