Comcast customer Ronaldo Boschulte didn't know exactly what he was getting when the company swapped his malfunctioning modem for a new one. The cable modem doubles as a Wi-Fi router—that much he was expecting. But he didn't realize the router would, by default, broadcast a public Wi-Fi network that anyone with a Comcast account could connect to.

“I didn't know it had a hotspot," Boschulte told the St. Paul Pioneer Press in Minnesota.

Comcast started adding the public hotspot to its modems by default in mid-2013, as we reported at the time. Customers can turn the second signal off if they choose, but it's definitely an opt-out program rather than opt-in.

Further Reading Comcast turns your Xfinity modem into public Wi-Fi hotspot

In an FAQ , Comcast doesn't provide instructions for turning it off manually. You have to call Comcast for that. "You will always have the ability to disable the XFINITY Wi-Fi feature on your Wireless Gateway by calling 1-800-XFINITY," the company says. Presumably, a customer service representative will try to talk you out of disabling it.

"We encourage all subscribers to keep this feature enabled as it allows more people to enjoy the benefits of XFINITY Wi-Fi around the neighborhood," the company says.

The second network won't slow your primary connection down, at least not much. "The broadband connection to your home will be unaffected by the XFINITY Wi-Fi feature," Comcast says. "Your in-home Wi-Fi network, as well as XFINITY Wi-Fi, use shared spectrum, and as with any shared medium there can be some impact as more devices share Wi-Fi. We have provisioned the XFINITY Wi-Fi feature to support robust usage, and therefore, we anticipate minimal impact to the in-home Wi-Fi network."

Comcast's own statements make it obvious that the company isn't going out of its way to help customers turn the hotspot off. Boschulte's experience is further proof—he said he only found out about the feature in an e-mail from Comcast after the new equipment was installed. But upon thinking about the public hotspot, he decided he liked it.

"I think it is a great idea how to expand their service. I think it is a great way to make the Internet and Wi-Fi available to a large audience," he told the Pioneer Press.

Others weren't so forgiving. The Pioneer Press quoted three customers who expressed concerns about performance, data privacy, and just general distrust of Comcast's customer service representatives.

Routers like Boschulte's broadcast a network called xfinitywifi. Comcast subscribers who connect to the network and sign in using their Comcast credentials gain access to the Internet. Comcast has said it aims to "create millions of Wi-Fi access points for its customers" with this so-called neighborhood hotspot initiative.