The outages are affecting pockets across the country, from the southeast to Washington state.

Comcast, one of America’s largest internet service providers, relies on network partners to deliver its services across the country. “You can think of the internet as like a pile of fishing nets that are independent, but sometimes connect to each other,” Andrew Blum, author of Tubes: A Journey to the Center of the Internet, told Quartz. “Sometimes a physical failure at one place could have an impact on networks that you didn’t realize are part of that infrastructure.”

Despite the talk of “the cloud,” Comcast users across the US were reminded again today that the internet is still a physical thing.

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