Comcast may be using your home router to broadcast a public wi-fi hotspot. Find out what that means, and how to get rid of it.

There are a lot of Comcast cable modems leased by residential and business customers. Millions, in fact. In 2014 Comcast created a public network on many of them called "xfinitywifi." If you're a Comcast customers, you can use this public hotspot to sign in — using your own e-mail address — to access the Internet. The network has confused and worried some of our readers, however. If you're one of them, here's what you need to know.

Millions of Comcast's residential cable modems were reprovisioned last year to broadcast the "xfinitywifi" network, along with thousands of business cable modems. The bandwidth used by the network doesn't count against your own bill; it's a free service for Comcast customers.

If you rent your modem from Comcast, chances are your modem is broadcasting an "xfinitywifi" network.

That in and of itself isn't necessarily a bad thing. It means that other Comcast customers can come over to your house and log on to Wi-Fi without accessing your personal network at all. So if the presence of "xfinitywifi" doesn't bother you in the list of available networks, feel free to ignore it.

If you're having trouble with xfinitywifi — if you're unable to log on, or if your Mac is really slow — you should be able to just switch back to your own network by clicking on the Airport menu item and selecting your preferred network from the list.

You can also reorder the way your Mac will connect to networks by opening the Network control panel.

To reorder network preference and forget xfinitywifi

  1. Open Spotlight by pressing the command key and then pressing the space bar.
  2. Type network and hit return.
  3. Look for a System Preference called Network and double-click on it.
  4. Click on the Advanced button.
  5. Make sure your preferred network is dragged to the top of that screen. If you want to forget about xfinitywifi all together click its name in the list and then click the "-" button.
  6. If iCloud Keychain is active, click Remove.
  7. Click OK.
  8. Click Apply.

That'll make your Mac forget xfinitywifi ever existed. If you use iCloud Keychain, all connected devices will forget about xfinitywifi too.

You can take it a step further and eradicate xfinitywifi all together. A simple call to Xfinity tech support should get them to turn it off on your router.

Even if you do that, there's no guarantee xfinitywifi will disappear. It depends on how close you are to your neighbors. I can still see the xfinitywifi hotspots my next door neighbors are broadcasting just fine. But at least you'll have the peace of mind that your cable modem isn't being used for anything you don't know about.