Why Your NBN Speeds are Slower Than What You Pay For

Why Your NBN Speeds are Slower Than What You Pay For
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NBN speed tiers seems pretty straight forward. The higher the number the faster the connection. But what your plan says you should get isn’t what you actually receive in the real world. Here’s why.

Different NBN Speeds explained

NBN plans are categorised by their speed tiers. This basically means they are defined by the maximum download and upload speeds available via an optimal connection. This is measured in megabits per second (Mbps).

For example, an NBN 100/20 plan means it can theoretically get 100Mbps down and 20Mbps up.

But just because a connection is capable of going a certain speed doesn’t mean it will. In fact, it generally won’t. This is because not all internet connections are made equal and a number of factors can impact the end result.

Some can get overly technical. For example, if a telco overcrowds a port. But you’re really getting into the weeds at that point. Here are the more likely and significant reasons for slower NBN speeds.

NBN congestion

You may have noticed that NBN service providers will advertise their “typical” evening speeds. This is important because it tells you how fast the connection is likely to be during the busiest time of day – 7pm to 11pm. This is when most users are using the network simultaneously.

It’s also the most significant factor when it comes to speed being impacted. The more people online, the more congested the network.

It’s such a crucial element that the ACCC releases a quarterly report that ranks the typical evening performance of Australian NBN providers.

While every service provider experiences congestion, it’s not in equal measure. Here’s how major NBN providers fare:

So why does congestion happen? The main culprit is Connectivity Virtual Circuit (CVC).


On top of paying for access to the network itself, NBN service providers like Aussie Broadband and Optus  pay a CVC charge to NBN Co to access bandwidth. The more CVC a provider reserves, the more bandwidth they have available to guarantee NBN speeds during peak hours.

This is how NBN Co explains it:

“Think of this as the thickness of a pipe that determines the maximum amount of water flowing through – which is why the peak time of day is considered when determining how much flow through an RSP needs to adequately serve its customers. While the amount of CVC purchased limits the total volume of data being passed between the two networks, the more practical impact of not purchasing enough will constrain the observed speed during busy traffic times.”

CVC is so crucial to NBN speeds that NBN Co released 40 per cent extra CVC to all NBN providers during COVID-19. This was because of the sheer number of people who began working and studying from home, as well as staying indoors more often in general.

While the offer was only supposed to be in effect for a couple of months, it has been extended twice due to the state of the virus in Australia.

Interestingly, several Australian telcos don’t seem to like the CVC model. You can read Aussie Broadband’s take on it here. Telstra even backs the company up.

There’s a little more to it…

But it isn’t just CVC that needs to be purchased by service providers to keep NBN speeds at a decent level. They also need backhaul and transit.

Backhaul is the connection between your telco and NBN Co. Transit is the connection between your telco and the wider internet.

Both backhaul and transit are cheaper than CVC but can still impact the speeds if an adequate amount isn’t purchased. In general a telco will buy the same amount of backhaul and transit per customer as CVC.

NBN Connection Type

There are seven different NBN connection types in Australia, with some being superior in terms of speed and service than others.

The problem is that NBN speed tiers are often available across multiple connection types – but that doesn’t mean you’ll get the same speed.

For example, NBN 100 is available across several different NBN connection types. But a Fibre to the Premises (FTTP) connection is generally going to be faster than a Fibre to the Node (FTTN) connection.

This is because FTTP connects your home directly to the NBN via a fibre optic cable. As such, it has the lowest speed degradation and highest potential for download and upload speeds due to how close and direct the connection is. Comparatively, an FTTN connection is slower because it lacks a direct fibre connection to the home.

Instead, it uses older copper phone cables to connect your home to the a central node in your neighbourhood. From there a fibre optic cable then runs from the node to the nearest fibre distribution hub.

Knowing your connection type is important because it is not factored into the typical evening NBN speeds that telcos advertise. This is because these speeds are just an indicator of what you should get on a optimal connection. But as we can see from the above, not all connections are optimal.

If you’re interested in learning more about the different NBN connection types in Australia (and which NBN speed tiers work on each) we have a big explainer here.

I don’t know what type of NBN connection I have

If you’re not sure what type of NBN connection you have, don’t worry. We have a tool to help you with that.

Once you pop you address in it basically populates the best possible plans for your NBN connection, based on your home or office address.

The tiny information icon will tell you what NBN connection is available at your address:

If you don’t have NBN access, it will let you know if it’s coming to your area soon. It will also show you ADSL plan alternatives, like home wireless

Other NBN Speed factors

There are a couple of other things that can impact your NBN speed. It’s possible that you have old wiring in your house. You might also have a less than ideal modem or router.

Replacing these (admittedly the wiring would be a big job) could help improve the download and upload speeds in your home.

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