Hackers are carrying out a "malicious" cyber attack on Telstra, creating connectivity issues for some home internet users.
Telstra reported the denial of service attack on its servers on Sunday which has led to widespread internet outages in Australia's eastern states.
A denial of service attack floods a network with traffic or information to trigger a crash, denying legitimate users access.
Melbourne, Sydney and Brisbane are the main outage hotspots.
Other internet providers have not reported connectivity issues despite reports of NBN problems spiking just before 11am.
The telecommunications giant said it was confident it had now blocked all "malicious traffic" and is continuing to work on getting users back online.
Telstra insists customers' personal data hasn't been compromised and apologised for the outage.
"Your info isn't at risk," the company tweeted.
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