- China web traffic was blocked from accessing outsider websites
- No political or sensitive events appear to have coincided
- Pakistan also suffered an outage hours before
China appears to have shut itself off from the internet world for over an hour earlier this week, but could it have just been a mistake?
The country’s “Great Firewall” disrupted all traffic on TCP port 443, used for HTTPS, for 74 minutes on August 20, 2025, but with most citizens asleep during the outage (00:34-01:48 Beijing time), was this intended behavior?
Interestingly, only port 443 was affected, leaving other ports like 22 (SSH), 80 (HTTP and 8443 (alterative HTTPS) unaffected.
China just had a partial internet outage
By injecting forged TCP RST+ACK packets to cut connections on port 443, the Great Firewall blocked access to most websites outside China and also disrupted services that rely on offshore servers, including Apple and Tesla.
A report explained the Great Firewall of China is not a single entity, but a “complex system composed of various network devices that perform censorship.” The device involved did not match fingerprints of known GFW equipment, suggesting the 74-minute outage could have come from a new censorship device, a misconfigured known divide or a test of port-blocking capability.
The Great Firewall also has a history of glitches, leaks and other technical errors.
Unlike past censorship events, no major political or other sensitive events were identified during this outage, making the reason more obscured.
Coincidentally, Pakistan also saw a large drop in internet traffic hours before the Chinese outage. The two countries both have similar histories of web censorship, and China has even been linked with sharing censorship technology with Pakistan, potentially drawing a link between the two events.
More broadly, the granular and more complex censorship that China chooses (compared with total shutdowns observed in Turkey, Sudan and Egypt) strikes a fine balancing act between restricting access to foreign information while avoiding economic harm.
With the community responding to the report’s comments with suspicions that this could have been a test, we’re left with little more evidence than to believe either this is the case, or it was a mistake.