South Korean telecommunications operator KT suffered a nationwide network outage on Monday, causing widespread disruptions to daily tasks requiring connectivity. Virtual classrooms were down, food delivery orders were lost, and clinics couldn’t access patient data. 

The network outage, which began around 11 a.m. and lasted for nearly an hour, was initially said to have been caused by a cyberattack. A local police station dispatched a team of cybercrime investigators to KT’s headquarters in Seongnam, Gyeonggi Province, just south of Seoul, but later said they had found no significant evidence of a DDos attack, or a distributed denial of service attack.

Also later in the day, KT restated that the outage appeared to have been caused by routing errors, not by large-scale DDos attacks. A routing error can cause connectivity problems in the process of transmitting and routing IP packets for the internet. 

The firm said it was still looking into the exact cause of the nationwide network outage, and apologized for the inconvenience.

“We are promptly responding to the situation by operating the firm’s risk management committee. We will do our best for a quick recovery,” KT said in an announcement.

KT said it had held an emergency meeting to discuss whether to continue with the police investigation.

While the network was down, KT users lost internet and phone service. Securities companies using online and mobile trading programs also experienced inconveniences.

Stores using KT service for payment systems failed to process credit card payments and were forced to ask customers to pay via cash or bank transfer. Students taking online classes were unable to participate. 

At around noon, connectivity was restored for both wired and wireless services. But in some regions, phone calls still were not going through. 

According to the Science and ICT Ministry data, around 14.3 million people relied on KT for internet service as of March 2021. 

In 2018, KT suffered a network outage after a fire at its Ahyeon branch in central Seoul. The fire caused internet and phone service disruptions in nearby areas, including the Seoul districts of Jung-gu, Yongsan-gu and Seodaemun-gu.

By Kim Da-sol (ddd@heraldcorp.com)