SAN FRANCISCO — Alphabet, the parent company of Google, is signaling a strategy shift for one of its most ambitious and costly efforts: bringing blazing-fast web connections to homes across America.

The company said on Tuesday that it was curbing the expansion of its high-speed fiber optic internet network and reducing staff in the unit responsible for the work. Alphabet did not provide an exact number for the jobs that will be cut.

Craig Barratt, chief executive of Access, the Alphabet division containing Google Fiber, also said he planned to step down because the company was shifting to new technologies and methods of deploying high-speed internet. No replacement was announced. Mr. Barratt, an Alphabet senior vice president, said he would remain an adviser to the company.

When Google introduced Fiber in 2010, it was heralded as a sign of the company’s ambitions to compete against cable and telecommunications operators who have controlled the market for internet access. But after years of costly investments to dig up roads and lay fiber optic cable, Google started considering alternatives, including wireless and fiber partnerships, that did not necessarily require the company to build a full network.