Fault finding & troubleshooting
Is your NBN dropping out?
If your NBN keeps dropping out, the cause is very often inside the home: old phone sockets still on the line, a worn adaptor or lead, or a crowded power board. Here are the causes we find most, two of them with a real job on video, and how to tell them from a fault in the network.
NBN dropping out?
The service connects, works for a while, and then the lights on the NBN box or the modem drop and come back. Sometimes it is the network. Often it is something inside the home or office, and those causes can be found and fixed on site.
This page goes through the ones we find most, in the order we check them. First, the one test that saves the most time.
Check your speed first Plug a laptop into the modem with a cable and watch it for an hour. If the cable is steady and only WiFi drops, skip to the last section. If the cable drops too, start at the top.Your home wiring
Most Australian homes were wired for the plain old telephone service. A house would have three to six phone sockets, and every one was live, so a phone worked wherever you plugged it in. ADSL worked on that wiring too: plug the modem into any socket.
The NBN does not. On fibre to the curb, fibre to the node and fibre to the building, the service wants one direct line from the street to one socket. The old sockets are wired in one of two ways, and both get in the way.
Star wiring
In a star-wired home, a cable runs from each socket back to a single point. Sometimes that point is the first socket. More often it is a joint in the ceiling or under the floor. In a well-wired home it is a small frame where every cable ends neatly.
Daisy chain wiring
In a daisy-chained home, the cable goes from the first socket to the second, from the second to the third, and on down the line. A great many homes are wired this way.
Where the phone cable runs
A house with four phone sockets, seen from above.
- The line your internet runs on
- The joining point
- Still on the line: a bridge tap
- The line your internet runs on
- Still on the line: a bridge tap
- Street to one socket, nothing else
- Disconnected from the line
Star. A cable runs from each socket back to one joining point, often a joint in the ceiling. The three sockets the modem is not using still hang off the line, and each one is a bridge tap.
Read: Star wiring, and What is a bridge tap?
Daisy chain. The cable runs from the first socket to the second, from the second to the third, and on down the line. Every socket past the one the modem uses is a bridge tap.
Read: Daisy chain wiring, and What is a bridge tap?
Fixed. The lead-in from the street goes straight to the one socket the NBN box or modem plugs into, and every other socket is taken off the line.
Read: How to fix it
Why this is a problem
Either way, the line your internet runs on has other cables and sockets hanging off it. Each of those is a bridge tap, and on fibre to the curb, fibre to the node and fibre to the building it can drop the service out.
What is a bridge tap?
A bridge tap is any phone socket still connected to the line that is not on the direct path from the street to the socket you use. The signal from the street runs up the spare cable, reaches the dead end and bounces back. The NBN box or the modem then receives the signal and its echo, cannot make sense of the two, and drops the connection.
There is a full explanation in what a bridge tap is.
How to fix it
The fix is the most direct route possible: the lead-in cable from the street joined straight to the one socket the NBN box or modem plugs into, with every other socket taken off the line. The existing cable can be reused if it tests well. You can have the old sockets taken off the line and one socket put where the modem should be. Losing them from the internet does not have to mean losing the phones in the rooms: phone line repair puts those phones back.
In this job, a socket relocation turned up a lead-in joined onto old cable running to three places in the house.
Watch: Your NBN Dropout Problem Solved | Bridge Tap Removal & Socket Relocation
Adaptors and the old 610 socket
The 610 is the old phone socket: a large plug with three flat pins, usually cream or yellow. The NBN box and modem leads have a small modern plug, so a 610 socket needs an adaptor.
Adaptors cause a lot of trouble. If one is not pushed fully home, or its copper contacts are tarnished or corroded, the join has high resistance, and that is enough to drop the service. Old ADSL filters left on a socket do the same.
The lasting fix is a modern wall socket in place of the 610, so no adaptor is needed.
Watch: One Tiny Corroded Part Destroyed Her Internet Connection
Old leads
Use the new leads that came with the NBN box and the modem. An old lead can have bent pins or corroded copper, and either will drop the service. A damaged lead plugged into another socket in the house can do it too, by shorting the line.
Power boards
A cheap power board loaded with the NBN box, the modem, the TV and a games console can drop the service. When one device draws a surge, the others on the board feel it, and the NBN box or modem resets.
The sign is that every light on the box goes out and comes back at once, power light included, not only the connection light. Give the NBN box and the modem a wall socket of their own.
Network faults
Sometimes it is the network. On fibre to the node especially, the line still runs through old copper cables and joints in the street. Those can be wet, corroded or damaged, and the further you are from the node, the weaker the signal that reaches you.
A network fault is the provider’s to arrange and NBN’s to fix. What helps is proof that your own wiring is clear, which is what an independent NBN technician tests to the boundary. On one job the home’s cabling tested within specification and the short circuit was found on the network side.
There is more on what is in the old copper network in faults in the Telstra network, and on weather in fibre to the curb dropouts when it is windy or raining.
WiFi
If the internet is fine near the modem and drops at the other end of the house, that is not the NBN and not the wiring. It is WiFi coverage.
There are two fixes. Data cables to WiFi points placed where the house needs them give the steadiest result. A mesh system gives whole-house coverage without running cables, and suits most homes. A WiFi technician can set up either.
See how to boost a mesh WiFi signal and do WiFi range extenders really work. If the service stays up and is slow, see why your NBN is slow; if it stays up and keeps stalling, see why an internet connection is unstable.
What to check yourself, in order
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Test on a cable
A laptop plugged into the modem. Steady there means WiFi. Dropping there means the line.
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Unplug the other sockets
Old phones, a fax, ADSL filters, an alarm dialler. Everything except the NBN box or modem.
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Use the first socket and new leads
No extension lead, no splitter, and the leads that came in the box.
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Give it its own power point
The NBN box and the modem on a wall socket, not a shared board.
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Write down when it drops
Time, weather, and what the lights did. Then report it to your provider with that list.
To make that list hard to argue with, log the drops with PingPlotter while they happen.
The cheapest fixes really are the most common ones. In our 2026 fault report, a small part like a coupler or patch lead was the advice that solved the most problems without a visit.
Still dropping out after all that? Start a fault log before you ring your provider again.
Frequently asked questions
Why does my NBN keep dropping out?
On fibre to the curb, fibre to the node and fibre to the building, the most common cause inside the home is old phone sockets still connected to the line. After that come worn adaptors and leads, a crowded power board, and faults in the network. If it only drops on WiFi and a cable is steady, it is WiFi coverage, not the NBN.
Can I use an old 610 phone socket for the NBN?
It will work with an adaptor, but it is a weak point. The 610 is the old three-pin phone socket, and the NBN box or modem has a small modern plug, so an adaptor sits between them. A loose or tarnished adaptor is a common cause of dropouts. Replacing the socket with a modern one removes the adaptor.
Do I need an ADSL filter on the NBN?
No. ADSL filters were for sharing one line between a phone and a modem. On the NBN they do nothing useful, and an old filter left plugged into a socket can cause dropouts. Unplug them all, along with anything else on the other phone sockets.
How do I know if the dropouts are NBN's fault or mine?
The line can be tested where it arrives at your property, with your own wiring disconnected. If the fault is still there, it is on the network side. If the line is clean there and faulty at your socket, it is in the home. That test is what settles it, and the result can be put in writing for your provider.
Need this fixed rather than explained?
This is written from the field. When the fault needs a technician on site, this is where to go next.