Amazon Web Services (AWS) has had a bad day. That's how the boss of another big US tech firm Cloudflare put it – probably feeling very relieved that today's outage, hitting over 1,000 companies and affecting millions of internet users, had nothing to do with him.

Amazon Web Services, a major provider of cloud hosting that underpins much of the web and everyday online tools, went offline because of a problem with one its core database products.

Disruptions lasted upward of two hours for most services, though some users—mostly in the United States—continued to see problems for over six hours. AWS announced at 5:27 a.m. ET that core issues had been resolved and most services were recovering, but intermittent disruptions persisted into the morning.

Amazon Web Services, a cloud computing service run by Amazon, experienced a significant outage that disrupted numerous websites on Oct. 20.

Experts say the incident revealed what can happen when a such a broad spectrum of companies rely on singular cloud provider.

Internet users around the world faced widespread disruption early Monday because of a problem at Amazon’s cloud computing service.

The massive Amazon Web Services outage that took down sites from Reddit to Ring to Roblox has been fixed, the company said. The AWS outage rendered huge portions of the internet unavailable for most of the work day for many people on Monday.

Monday’s Amazon Web Services outage — and the global disruption it caused — underscored just how reliant the internet has become on a small number of core infrastructure providers.