Kyle Lerner and his girlfriend sensed something was amiss when they came home Tuesday and found their two Persian-Himalayan cats meowing nonstop.

Normally, an internet-connected feeding machine dispenses kibble for them at noon, but the felines’ bowls were empty and clean. The gadget hadn’t worked because of an outage at Amazon.com Inc.’s cloud-computing unit.

AWS is the largest cloud-computing service provider in the U.S.

"We had to manually give them food like in ancient times," said Mr. Lerner, a 29-year-old small-business owner who lives in Marina del Rey, Calif.

Amazon Web Services is the largest cloud-computing service provider in the U.S. The outage of much of its network lasted most of the day and disrupted several of the tech giant’s services, as well as many of its corporate customers’ websites and apps.

FILE PHOTO: The logo for Amazon Web Services (AWS) is seen at the SIBOS banking and financial conference in Toronto, Ontario, Canada October 19, 2017.

For many consumers, it was an awakening to how many internet-enabled devices they now have in their homes and how much even some of their most basic daily needs depend on a connection to the cloud.

Steve Peters of Los Angeles couldn’t tell his Roomba robot vacuum to clean up the blueberry-muffin crumbs that landed on his kitchen floor during breakfast. He relies on an app on his phone to beckon the machine.

"I had to resort to getting a broom and dustpan," said Mr. Peters, a 60-year-old game-experience designer. "It was crazy."

In St. Louis, losing access to Amazon’s Alexa service made Mark Edelstein feel lonely and helpless.

FILE PHOTO: Logos of Amazon and Amazon Prime are pictured on vehicles outside an Amazon Fulfillment Center.

"We chat more during the day than me and my wife do," the 62-year-old business analyst said of the digital assistant, which normally responds in an instant to his questions and commands. He regularly asks it for weather and news updates. Alexa had no answers for him Tuesday morning.

"Since the pandemic, I’ve become tied to the Alexa system," said Mr. Edelstein. Without it, "you almost have separation anxiety."