“Net neutrality has been killed at the behest of large carriers and network companies,” said Om Malik, a partner at True Ventures and longtime Silicon Valley commentator. “Technology needs to figure out a way to increase competition.”

One way might be through virtual private networks, or VPNs, a technology that businesses use to let remote workers connect to a secure online portal. Some VPNs help users shield their physical location and browsing patterns from internet service providers or governments, such as in Saudi Arabia, where users relied on the software to circumvent a statewide block of voice-calling service Skype last year.

“We have been fighting this net neutrality battle in other countries over the last five years,” said David Gorodyansky, chief executive of AnchorFree Inc., a Menlo Park, Calif., startup that provides VPN service Hotspot Shield. “We are going to do the same in the U.S.”

Americans could use a service like Hotspot Shield to cloak their digital whereabouts from broadband providers. In theory, that would make it harder for telecom companies such as AT&T Inc. or Verizon Communications Inc. to slow down a site or completely block users from viewing it.

One problem with VPNs is speed. The online services most in danger of being blocked or throttled include video-streaming sites and other high-bandwidth applications, which generally take longer to load when connecting through a VPN. AnchorFree has also drawn concerns about how it collects user data for the purpose of selling ads, according to a complaint filed with the Federal Trade Commission earlier this year.

Mr. Gorodyansky, whose company has raised more than $62 million from investors including Goldman Sachs Group Inc., said his service is only “slightly slower” than normal web browsing. He said the company doesn’t sell users’ data to third parties.

A mesh network may be another alternative to traditional internet access. Instead of accessing the internet through one provider, users of a mesh network pull bits of information from many different nodes—such as phones, laptops and antennas—around them, and often serve as a node themselves.

That is the idea behind Ms. Perdomo’s company goTenna Inc., which makes a strap-on antenna the size of a smartphone that can connect with sister devices several miles away using a radio signal. The devices sync to phones for a connection strong enough to send encrypted texts and GPS coordinates between devices.

As more antennas are added to the network, the messages can be sent over distances surpassing 4 miles. Rather than Wi-Fi or cellular signal, goTenna relies on publicly available radio frequencies.

Ms. Perdomo, a New Yorker who dreamed up goTenna when Hurricane Sandy rendered the city’s cellphone service unreliable in 2012, said her broader goal is to build a free, “bottom up” communication network accessible to all and more reliable than the “top down” networks controlled by a few large companies.

Matt Filip, a 33-year-old field engineer in Downers Grove, Ill., bought a goTenna earlier this year and has since used it to communicate with friends on hunting trips in remote locations. He said he likes the idea of commanding an alternative network to wireless carriers and plans to set it up at home to support other goTenna users.

Another vision of mesh networks is taking shape in Porto, Portugal, where startup Veniam worked with city officials to install wireless sensors on moving vehicles, including buses and garbage trucks. The vehicles connect to Wi-Fi hot spots and to each other to create an internet network that reaches more people in more places. Veniam has deals with carriers including Vodafone Group PLC, which provides free wireless access to bus riders and other Porto residents.

João Barros, Veniam’s founder, says a system like this only works when wireless internet providers treat different users of data equally.

“I imagine there may be a scenario where they will compete with each other to provide a more open policy,” Mr. Barros said. Among his investors: mobile carriers Verizon and Orange SA .

Write to Douglas MacMillan at douglas.macmillan@wsj.com

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Appeared in the December 28, 2017, print edition as '.'