“A large number of people are aware of the situation and they are not O.K. with it,” said Nikita Likhachev, editor in chief of TJournal, an online publication covering internet culture, technology and politics.

With no public accountability, nobody has any real sense of the scope of the shutdown, he said. “The whole point about the internet being broken in Russia is that we don’t know what is happening and whether it can be fixed at all,” Mr. Likhachev said.

Countless people who play online games or use specialized services and tend to be apolitical, Mr. Likhachev said, have suddenly realized how much the government can affect their daily lives. “They have started asking questions about what is happening,” he said.

At the rally, which was peaceful, one hand-painted sign reflected that mood: “Things are so bad that even introverts are here.”

No arrests were reported.

The rally, organized by Russia’s small Libertarian Party, had an official permit — often a sign that the government knows that a broad segment of the population is angry. The roster of speakers included opposition stalwarts like Aleksei A. Navalny, the anticorruption activist. He led chants of “Down with the Czar!” and called on people to continue to fight censorship at the May 5 rally he has called nationwide to protest Mr. Putin’s inauguration for a fourth term.

Various speakers and demonstrators said they had never been to any public demonstration before.

Alexander Gornik, 34, a software entrepreneur, said many of the tools that his employees use for work, like Slack, Pipedrive and Tralier, were now inaccessible. To make high-quality software that can compete globally, Russia needs to be connected to the world, he said.

“This is not just about Telegram, it is an attempt to isolate the Russian segment of the internet,” Mr. Gornik said.