Those who use Comcast's Xfinity-branded residential-gateway broadband routers, which combine a cable modem with an Ethernet and wireless router, could find themselves becoming mules for the company's publicly available network. Comcast can turn on a second Wi-Fi signal in its customers' home routers that could be used by anyone with an Xfinity account — even total strangers who happen to be driving by.

The company has already activated this feature on hundreds of thousands of routers all around the United States. It intends to turn on millions of these hotspots in the coming months.

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Comcast states on its website that the feature is not available to those subscribed to Comcast's Economy Internet package.

A Comcast Internet technical-support representative told us after this story was first published that the Arris TG862G and Technicolor TC8305 models support the public Wi-Fi hotspot feature, while Cisco and SMC models do not as of yet. While the Cisco devices do have two antennas, they're only for dual-band Wi-Fi in the home, said the tech-support rep. The SMC models have only one antenna.

If you use one of the affected models, you might want to turn the home hotspot feature off. While we don't expect there to be severe security risks with the second network being opened up, it is likely that more people using your hotspot could slow your overall Internet connection.

Prevent that from happening by tuning off the home-hotspot feature. Make sure your Comcast username and password are handy, and follow these easy steps to turn off the second signal in your Comcast router. You can also check Comcast's website for a more comprehensive how-to in case you have a newer router.

1. Go to http://customer.comcast.com.

2. Log into your account.

3. Select Users & Preferences from the top navigation bar.

4. Click "Manage Xfinity WiFi" under the Service Address section.

5. Select "Disable Xfinity WiFi Home Hotspot" in the dialog box that pops up. If you don't see the option to enable or disable the home hotspot, the feature may not have been activated in your area, or your modem/router combination may not be compliant.

6. Save your changes.

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