Chinese internet users faced an unusual disruption on August 20 when access to most global websites was cut for about an hour. Blackout left millions of people unable to join popular international platforms and services, questioning whether it was a technical mistake or deliberately testing China’s strict online controls.

The disintegration was first identified by the Great Firewall Report, which tracks how China’s censorship system behaves. The group said the issue started at 12:34 pm and went to Beijing time till 1:48 pm. During this period, all traffic going through TCP Port 443 (standard port used for HTTPS connection) was blocked. Because this port is required for safe websites, blackout meant that users could not reach most of the services hosted outside China.

The group wrote in its report, “Between about 00:34 and 01:48 (Beijing Time, UTC + 8), the great firewall of China demonstrated anxious behavior by injecting the unconditional TCP RST + ACK packet to disrupt all connections on TCP Port 443.

The effect was not limited to browsing. Many services depend on Port 443 to work with cloud platforms, apps and even car services. For example, Apple iCloud and Tesla’s connected car systems rely on this port to link with servers abroad. With the channel being blocked, Chinese users were unable to reach these platforms during outage, while domestic sites within China remained unaffected.

Internet restrictions are not new in China. The country already runs one of the most advanced censorship systems in the world, usually called Great Firewall. It blocks access to foreign news outlets, social media and services that do not comply with Chinese laws. But suddenly, nationwide block on Port 443 is unusual. In the past, authorities have tightened restrictions during political events or moments of public sensitivity. This time, however, the register, which reported on disintegration, said that there was no major incident on August 20 that could explain the move.

The Great Firewall Report also described something unusual in its analysis. The equipment responsible for the shutdown did not match any known fingers of existing sensorship devices. It has speculated that Chinese officials are testing new hardware, or that a technical error caused unexpected behavior. Experts suggest two main possibilities. It was either a deliberate examination to see if the system could block 443 nationwide ports, or it was a misconception within the network.

Such incidents suggest that the great firewall, despite its reputation, is not innocent. In the past, it is a mess, leak information, or left itself open to cyber attack. Analysts often argue that the scale and complexity of China’s censorship system means mistakes. At the same time, blackout shows how much disintegration can occur for ordinary internet users.

Outage time has also attracted attention. A few hours before China’s blackout, Pakistan saw a sharp decline in its internet traffic, according to the monitoring group Netblock. It is believed that Pakistan has adopted the censorship system affected by China’s technology, although whether two incidents are attached, it is not clear.

So far, Beijing has not issued any official explanation for the 20 August shutdown.