When your internet suddenly drops or starts crawling at a snail’s pace, the likely cause is one of many possible NBN faults. These faults can be frustrating, especially when you rely on a stable connection for work, entertainment, or family communication.
This comprehensive guide will walk you through everything you need to know about NBN faults—what they are, how they happen, and what steps you can take to fix them yourself before calling in the pros.
NBN faults are problems within the National Broadband Network that prevent users from accessing stable, high-speed internet. These issues can arise in the core network infrastructure or within your property’s internal wiring, modems, or NBN boxes.
Faults might result in:
Slow download/upload speeds
Connection dropouts
No internet access
Inconsistent signal strength
Device disconnections
Whether the problem lies in external lines or inside your home, recognizing the signs early can save time and stress.
Some NBN faults are due to aging infrastructure or environmental wear and tear, while others are caused by internal cabling or misconfigured equipment. The most common reasons include:
Water-damaged cables during rain
Loose or broken connectors
Power outages disrupting network sync
Faulty Network Termination Devices (NTDs)
Router or modem issues
Bridge taps or interference from internal wiring
Knowing the root of the problem can help you address it faster and avoid unnecessary technician visits.
Here are six easy and effective troubleshooting steps for diagnosing and fixing NBN faults yourself:
Your NBN box or modem displays several status lights that can indicate network health. If you see red, amber, or no lights at all, it usually signals a problem.
Power Light Off: Check the power outlet and NBN device plug.
Optical Light Red/Off: Likely a fibre line issue or external fault.
UNI-D Port Light Off: No data signal—modem may not be receiving the connection.
Each of these symptoms could be linked to underlying NBN faults needing either a restart or professional fix.
Sometimes the solution is as simple as turning everything off and on again. Power cycle your modem and NBN box by:
Turning off both devices
Waiting 60 seconds
Turning the NBN box on first, then the modem
This clears minor glitches that could be causing NBN faults and re-establishes the network handshake.
If you're using a wired connection, the issue could be a faulty port. Try moving the Ethernet cable to a different UNI-D port on your NBN box. This can help identify whether the original port is malfunctioning.
Many NBN faults are isolated to just one port, and switching may bring your connection back without needing service.
Modems and routers have a shelf life. If yours is more than five years old, it could be causing NBN faults such as dropouts, slow speeds, or device conflicts.
Borrow a newer model to test the connection. If speeds improve or the connection stabilizes, you’ve found the culprit.
Internal copper or fibre cabling can deteriorate, especially in older properties. Poor-quality wiring can lead to interference, signal loss, or frequent NBN faults.
Look out for:
Discoloured or frayed wires
Cable joints exposed to moisture
Unshielded phone line extensions
Fixing or replacing outdated cables can eliminate recurring NBN faults and improve speed dramatically.
If you've tried all of the above and your connection is still unstable, contact your ISP and report the NBN faults. They can run remote diagnostics, confirm if there’s a wider outage, or schedule a technician visit.
You’ll usually be given a fault reference number and updates while the issue is being resolved.
Prevention is key to avoiding NBN faults in the long run. Here are a few smart habits to keep your connection stable:
Regularly update your modem firmware
Keep the modem and NBN device away from moisture and heat
Use surge protectors to guard against electrical faults
Don’t overload your WiFi network with too many devices
Schedule periodic checks of internal wiring
By staying proactive, you can catch minor issues before they turn into bigger NBN faults.
Not all faults can be resolved with DIY fixes. If you're still facing problems after basic troubleshooting, it's best to consult a licensed NBN technician.
They can:
Test line quality with advanced tools
Rerun or replace faulty lead-in cables
Relocate or replace the NBN box
Repair bridge taps or damaged wall outlets
If you're constantly resetting your modem or struggling with weak signals, you could be dealing with hidden NBN faults that only a trained expert can detect and fix.
No one wants to deal with slow or broken internet, but NBN faults can happen at any time. The key is understanding the signs, acting quickly, and knowing when to escalate the issue. From blinking lights to broken wiring, the causes vary—but the solutions are often simpler than you think.
If you’re regularly experiencing NBN faults and the basic fixes don’t work, it’s time to seek expert support. A professional inspection and repair can restore your connection and give you peace of mind.