Why is my NBN so slow?

Slow internet? Find out which kind first

“The NBN is slow” can mean four different things, and each has a different fix. One test, done twice, separates them.

Check your speed first Plug a laptop into the modem with a cable and test in the morning. Test again on the cable at about 8 pm. Then test once on WiFi in the room where it feels slow.

What your three results mean

What you see	The cause	Whose to fix
Cable is fast, WiFi is slow	WiFi coverage or the router	Yours
Cable is fast in the morning, slow at night	Congestion in the network	Your provider's
Cable is slow all day, and always has been	The limit of your line, usually fibre to the node	The network's. An upgrade may be available
Cable is slow all day, and it used to be fine	A fault: wiring, a joint, a lead or the modem	Yours or the network's. It needs testing

What did your tests show?

Cable fast, WiFi slow Cable fast in the morning, slow at night Cable slow all day, always has been Slow all of a sudden

1. NBN and provider
2. Line and NBN box
3. Your modem
4. Your WiFi
5. Your device

Look at: your WiFi

The NBN and your line are delivering. The WiFi is losing it between the router and the room.

Wireless against wired

Look at: the NBN network and your provider

Nothing in your home is at fault. Your provider is short of capacity in your area at the busy time.

Network congestion at peak times

Look at: the line and the NBN box

The line is as fast as it can go. On fibre to the node that is usually the distance from the node.

Your type of NBN connection

Look at: the line and the NBN box, then your modem

Something changed: a lead, a joint, the wiring or the modem. It needs testing to say whose it is.

Slow all of a sudden

If the cable is slow all day and nothing on this page explains it, that is the point to book an internet technician in Sydney to test the line.

If the phone is quick and only the computer is slow, the NBN is not the problem: is it your computer or your internet sorts it out in two minutes.

How the NBN’s structure affects your speed

Your provider does not own the line to your house. NBN does. Your provider rents access to it, and connects its own network to NBN’s at handover points called points of interconnect.

At each of those points, the provider buys a set amount of capacity to carry all of its customers in that area. If it buys enough, everyone gets the speed they pay for at any hour. If it buys too little, everyone on that provider in that area slows down together when the evening rush starts.

That is why two neighbours on the same street and the same type of NBN, with different providers, can have very different evenings. It is also the one kind of slow that changing provider can fix.

Network congestion at peak times

The busy period is roughly 7 pm to 11 pm, when most households are streaming. Providers publish a “typical evening speed” for each plan, which is the honest figure to compare, more than the headline speed.

If your cable test is close to your plan in the morning and well under it at night, that is congestion. HFC is shared with the street as well, so it can slow in the evening for its own reasons too: see how HFC works. Tell your provider, with the two numbers and the times. If it does not improve, compare the evening speeds other providers publish for the same plan.

Your type of NBN connection

The type of connection sets the ceiling.

• Fibre to the node (FTTN) runs over the old phone line from a cabinet in your neighbourhood. The longer and older that line, the slower the service, and no plan or provider changes it. See what fibre to the node is.
• Fibre to the curb and fibre to the building have a much shorter copper run and usually deliver what the plan promises on sound wiring.
• HFC and fibre to the premises can take the fastest plans.

Since September 2025 the plan names mean different things on different lines. On fibre to the premises and HFC, NBN raised its two most common plans well past the speeds in their names and added a faster one, so compare your result with the typical evening speed your provider publishes for your plan, not with the plan’s name. Fibre to the node and fibre to the curb were not boosted: there the line is the limit, and a dearer plan will not lift it. The current figures are on our NBN speed test page.

If you are on fibre to the node or fibre to the curb and the line itself is the limit, check whether your address can upgrade to fibre to the premises. Many can, and our FTTP upgrade service is about getting the new box in the right place. See the fibre upgrade explained, and which NBN connection is best to find out what you have.

Your modem and your home wiring

On the copper types, the wiring inside your home is part of the line, and it is where a lot of lost speed hides.

• Old phone sockets still connected. Each one is a bridge tap, and together they can take a large share of the speed. See what a bridge tap is.
• A faulty or corroded socket.
• A damaged lead-in cable between the street and the house.
• An old modem. One that is many years old may not keep up with the plan, and its WiFi will be the weakest part of the house.

Taking the unused sockets off the line and putting the modem on the first socket is the most common fix we do for a slow copper service. An old modem is worth replacing only after a cable test shows the line is delivering and the modem is not. See the best modem for NBN.

Wireless against wired

WiFi is slower and less steady than a cable, always. Distance, walls, the neighbours’ networks and the number of devices all take a share.

• For a TV, a games console or a work computer, use a network cable. If there is no cable where you need one, data cabling puts it there, and the data cabling cost estimator gives you a price range first.
• Put the router in the open, up high, as near the middle of the home as you can.
• If the far rooms are slow, the house needs more than one WiFi point. See how to boost a mesh WiFi signal.

If your cable test is fast, everything in this section is your answer and nothing is wrong with the NBN. When the house is the problem rather than the router, a WiFi technician can sort the coverage on site.

If only the computer is slow, check the Mac itself before you ring your provider.

Slow all of a sudden

A service that was fine last week and is slow now has had something change.

1. Restart the NBN box and the modem, in that order.
2. Check for an outage on your provider’s page, on mobile data.
3. Test on a cable. If the cable is fine, something changed in the WiFi: a moved router, a new device hogging the connection, a mesh unit that has dropped off.
4. Think about what is new. A phone or an old filter plugged into another socket. A new power board. Building work. Heavy rain.
5. Look at the leads. Swap the lead from the wall and the network cable to the router.
6. Report it if the cable test stays slow, with the numbers and the date it started.

Finding the fault in your home setup

If the cable test is slow all day, the checks above have not helped, and your provider says the line tests fine, the wiring between the street and your socket needs testing on site: the lead-in, the joints, the sockets, and in a unit block the building’s frame.

That is fault finding, and it is what we do: on the copper types, an NBN technician tests the line to the boundary, and where the fault is on the network side, how an NBN fault gets repaired explains what happens next. The line is measured where it arrives and again at the socket. The difference between the two readings is the fault, and it tells you whether it is yours to fix or the network’s.

For a service that drops out as well as running slow, see is your NBN dropping out and why an internet connection goes unstable. If the speed test is fine and games or calls still lag, that is jitter or packet loss, and there is a worked example in high latency for a gamer.