In the night of August 20, 2025, China experienced a significant internet disconnection from the global internet, lasting approximately 74 minutes. The disruption, which affected TCP port 443 crucial for HTTPS connections, is believed to be the result of testing new equipment for the "Great Firewall," according to the Great Firewall Report. This event highlights the vulnerability of global digital infrastructure and its impact on businesses reliant on continuous connectivity.

Researchers reported that Chinese authorities blocked traffic on TCP port 443 between 00:34 and 01:48 Beijing time, preventing access to foreign websites and disrupting cloud computing services dependent on external servers. It was noted that the "Great Firewall's" behavior differed from previous censorship attempts, as it specifically targeted port 443 by injecting forged TCP RST+ACK packets to terminate connections.

Market Signals

Sector Impacts: Internet-dependent companies like Apple and Tesla were operationally affected due to their reliance on port 443.
Supply Chain Volatility: The incident highlights the fragility of global, digitally interconnected supply chains. Any major disruption in China could lead to worldwide shortages and price surges.
Digital Infrastructure: This points to the need to diversify digital infrastructure and avoid reliance on single points of failure.

Stakeholder Impact

Affected Companies: Companies such as Apple and Tesla were directly impacted due to their reliance on port 443. Furthermore, all businesses with operations, supply chains, or significant customer bases in China faced the risk of disruptions and future instability.

Supply Chain Implications: The event highlighted the vulnerability of global supply chains to disruptions within China's digital infrastructure. This could lead to increased lead times, higher costs, and a greater need for supply chain diversification.

Action Timeline

Immediate: It is essential to assess and diversify reliance on existing digital infrastructure and develop contingency plans for potential disruptions.
Short-term: Monitor developments in China's censorship infrastructure and its impact on market access.
Long-term: Re-evaluate risk management strategies in China considering regulatory and technological advancements.

Risk Assessment

Regulatory Risks: China's evolving cybersecurity laws and data localization requirements continue to pose challenges for foreign companies.
Market Volatility: Such events contribute to market volatility, particularly for technology and manufacturing sectors with significant China exposure.
Geopolitical Tensions: Global geopolitical tensions can exacerbate the impact of any technological or regulatory disruptions.

Key Indicators

Signal for Market: The tests indicate increasing capabilities in internet censorship and the evolution of "Great Firewall" technologies.
Leading Indicators: Any future tests of new equipment or anomalous network behavior will be key indicators of larger shifts.

Regional Perspective

The outage suggests that Chinese authorities are testing new equipment for the "Great Firewall," highlighting China's strategy in managing and controlling information access. This could be part of broader efforts to enhance digital sovereignty and content control.

Immediate Implications

What's Next: China is likely to continue testing and enhancing its "Great Firewall" capabilities, potentially leading to intermittent disruptions or increased restrictions.
Time-Sensitive Opportunities or Risks: Businesses should assess their digital infrastructure resilience and develop strategies to mitigate the impact of any future outages.

What to Watch

Leading Indicators: Monitor any reports of additional tests or changes in "Great Firewall" behavior.
Expected Developments: China may increase its investments in censorship technologies to bolster control over information.
Key Decision Points: Business decisions regarding supply chain diversification and reliance on China's digital infrastructure.

Analysis

This incident demonstrates the ongoing evolution of the "Great Firewall" and China's ability to enforce granular censorship of digital communications. The targeting of port 443 suggests an increasing focus on securing encrypted connections. Businesses must prepare for further such tests and develop plans to adapt to an ever-changing digital landscape in China.