The telco tweeted that it was looking into an issue impacting home internet connections, including those on the national broadband network (NBN).
Telstra has had to backtrack on its claims a major outage that upset home internet services was caused by a "malicious" cyber attack on its servers.
Telstra has since confirmed it is now experiencing a Denial of Service attack.
Melbourne, Sydney and Brisbane are the main outage hotspots.
When this happens, users are told they've lost their network connection or internet access when they try to send data by connecting to an Internet Protocol (IP) address.
Some guidance for this can be found online, however those uncomfortable making this change should await Telstra's own fix for the problem.
"Sorry to mess with your Sunday plans", the company tweeted.
"Some of our Domain Name Servers (DNS) used to route your traffic online are experiencing a cyber attack, known as a Denial of Service (DoS)". We're doing all we can to get you back online.
"We've identified a cyber security attack which is seeking to attack some of our services", they said.
"We are confident we have blocked all of this malicious traffic and are working to get you back up and running again".