Can I use Airport Extreme to extend Xfinity wifi?

Nice work. If you now have the AirPort Extreme producing a wireless network that uses the same name and password as the Xfinity network, then the AirPort Extreme should be all set.

Power off both AirPort Express devices and temporarily move them close to the AirPort Extreme

Power up one AirPort Express for a minute or two, then hold in the reset button on the Express for 7-8 seconds and release. Allow a full minute for the Express to restart to a slow, blinking amber light

Click the WiFi menu at the top of the Macs' screen and look for a listing of New AirPort Base Station

Just below that listing, click directly on AirPort Express

The AirPort Utility setup "wizard" will open up and take a few seconds to analyze things, then display a screen that looks similar to the illustration below, except that you will see your devices pictured and network name displayed

Type in a device name that you want to call the AirPort Express

Click Next

The "wizard" will set up everything for you automatically and correctly. When you see the message of Setup Complete click Done

Power off the Airport Express and move it to a location that is about half way between the AirPort Extreme and general area where you need more wireless coverage. Power up the Express and it will hopefully receive a strong signal from the Extreme to extend the network.

Set up the other Express the same way, except assign a different device name to avoid confusion.

Things can get tricky when you try to have two Airports trying to wirelessly extend the AirPort Extreme. Post back when you have both AirPort Express devices up and running and we'll provide a few more tips on best performance.

"Take it from there" can mean a lot of different things.

First item.....it makes no sense to try to set up the Airport Extreme to extend the Xfinity network unless the AirPort Extreme is going to be located at least a few rooms away from the Xfinity router.....and....the Airport Extreme will connect back to the Xfinity router using a permanent wired Ethernet cable connection.

For example, if the AirPort Extreme and the Xfinity router will be in close proximity, they will both be broadcasting the same wireless signal. This will confuse wireless devices because they will not know to which signal to connect.....and, more importantly.....having two wireless routers in close proximity will very likely create unwanted interference effects, which will worsen the wireless.....not improve it.

So, before we take it from here, we need to know where to take it.

Please clarify whether the AirPort Extreme will be located at least a few rooms away from the Xfinity router.

Thanks, that helps.

Now, about the AirPort Express devices. If you plan to also have them extend the network using a wireless connection to the AirPort Extreme.....keep in mind that the Expresses must be located where they can receive a strong wireless signal from the AirPort Extreme.....and they must connect to the Airport Extreme wireless.....not the Xfinity wireless.

If you move the AirPort Extreme to the basement, a lot of the WiFi signal that will be broadcast from that location will be lost as it tries to pass through a very thick and dense basement ceiling and first floor. This won't be a problem if you are planning to locate the Expresses in the basement, but it will be a real issue if the Expresses are used to receiving a signal from an AirPort Extreme that was formerly located on the first floor.

If you move the AirPort Extreme to the basement and you plan to run Ethernet cabling to the location of each AirPort Express from the Xfinity router, then you can locate the AirPort Expresses wherever you want.

So, if you could provide a general outline of where devices will be located and how the Expresses will connect to the AirPort Extreme, we'll be able to give you a decent idea about how well things might work.

Next item, we need to know whether you will be using a Mac or PC to set things up. If you have a Mac, we need to know what operating system is installed on the Mac. If you are not sure about this, click on the the Apple icon in the upper left corner of the screen and then click on About This Mac. Post back with the OS X Version number that you see there.

If you are ready to run the long Ethernet cable, we can tell you how to set up the AirPort Extreme. Once the Extreme is set up, we can tell you how to set up the Expresses, but if they will be connecting to the Extreme using wireless, we can offer no guarantees on how well.....or even if....the Expresses will do what you want.

Connect the long Ethernet cable to one of the four LAN <--> ports on the back of the Xfinity router and run it to the location where the AirPort Extreme will be located.

Temporarily, turn off the WiFi on the computer and then connect your computer directly to the Ethernet cable and make sure that it can get a good Internet connection that way. If it can, then you know the Ethernet cable is working correctly and we can proceed to the set up of the AirPort Extreme.

Post back when you have confirmed that the Ethernet cable is working correctly.