Singtel-owned operator Optus pointed to technical issues related to its routers after a software upgrade for a 14-hour network outage which affected 10 million customers last week.

In a statement, the Australian business explained the blackout was due to a disconnect between its routers and the company’s IP core network following the completion of a routine software upgrade, which caused changes to routing information. 

“These routing information changes propagated through multiple layers in our network and exceeded preset safety levels on key routers,” it said, adding the upgrade led to a massive restoration effort in which it had to send technicians across multiple sites to physically reboot its routers. 

The outage began to affect customers including hospitals and government organisations in the early hours of Wednesday (8 November) and lasted until 6pm local time. 

Optus added there is currently no indication the internet blackout was due to a cyberattack or compromised data. 

“Given the widespread impact of the outage, our investigations into the issue took longer than we would have liked as we examined several different paths to restoration,” the company further stated. 

It claimed it has made changes to its network to prevent future disruptions, and the operator is reportedly assembling a specialist team dedicated to assessing the issue.