Over the past week, we have been working with customers impacted by the nbn and ADSL broadband disruption, which started last Thursday night and has continued to affect some of you during this week.

As I said earlier in the week, it was a complex issue to identify and solve, and there were also some flow-on issues with modems which resulted in different customers being affected in different ways. This has added to the challenge and I know how frustrating this has been for some of you.

I apologise again for the disruption, and in particular, for the length of time some of you have not been able to connect. I wanted to provide some more detail about the situation and to explain why some customers were still disconnected after we fixed the network issue on Friday last week.

Every night when most of us are asleep, we make hundreds of changes to our mobile and fixed networks that are designed to both maintain and improve the network’s performance. Last Thursday night was no different. We made 800 changes on our fixed network alone, which is a pretty typical night of updates.

Unfortunately one of those 800 changes – a software update to our Domain Name Servers – caused a number of servers to fail which resulted in a short outage of this function. Normally this would have limited impact however on this occasion it had a cascading effect on our broadband modems and gateways. This occurred when a regular ‘check in’ or ‘heartbeat’ signal used by our modems was not able to contact those servers. When the modems lost their ‘check in’ response it caused many of them to reset, reconnect to the network and attempt to update their settings. These events caused the initial disruption to service throughout Thursday night and into Friday when the network was stabilised.

Unfortunately, this process of resetting uncovered an unpredictable response from some of the modems and some of them continued to reset. This ongoing resetting continued for a small percentage of our customers across the weekend and into this week.

Correcting this problem in resetting the modems requires a factory reset for some of them, or a replacement modem for others. Where a replacement modem is required, we are providing it free of charge.

So the issue we’ve faced had nothing to do with a firmware or software upgrade to modems, as has been speculated.

All of these consequences have been unexpected and we are looking into what we can do to prevent them from happening again. Some of the modems did not respond in the way they’re designed to do, and we expect we’ll be able to address that through a software update. We’ll also be addressing the network fault itself.

Importantly, we continue to have confidence in our fixed network. We have invested substantially over many years. We will continue to do so as we bring new features and services into the network and the home including Telstra Air, nbn Voice and HD voice calling, HD Video streaming, Telstra TV and more, making it one of the most advanced networks in the world.

But we understand we have work to do to restore your confidence as well. I can assure you we will not stop until we do.