Slow NBN is one of those problems that makes a normal evening feel broken. The video call freezes, Netflix drops to blurry, and the game update that should take ten minutes takes two hours. Before you ring your provider — or pay extra for a faster plan — work through the steps below in order. Most slow NBN problems turn out to be something inside the house, not the network, and the whole diagnosis takes about fifteen minutes.
The key idea is simple: find out where the speed is actually being lost. Is it the line coming into your house, your Wi-Fi, or the plan itself? Each answer points to a different fix. Guessing usually means spending money on the wrong one.
Step 1: Check what speed you are actually paying for
Log into your provider’s account page or app and check two things: your plan’s speed tier, and its “typical evening speed”. NBN plans are sold in speed tiers — NBN 25, NBN 50, NBN 100, NBN 250, NBN 1000 and the newer NBN 2000 — and the number is the maximum download speed in megabits per second (Mbps).
The typical evening speed is the figure your provider must publish under the ACCC’s broadband speed claims guidance. It tells you what you should realistically get between 7pm and 11pm, when the network is busiest. If that figure is already well below what you want, no amount of troubleshooting at home will fix it. You need a plan change, not a diagnosis.
It is also worth knowing what “normal” looks like. The ACCC’s final Measuring Broadband Australia report (June 2026) found that fixed-line NBN services averaged 99.4% of their plan speed during busy evening hours. So if you are on NBN 100 and regularly seeing 30 Mbps at 8pm, that is not normal — something is wrong, and it is worth finding out what.
Step 2: Run a wired speed test first
This is the single most useful test, and it is the one most people skip. Plug a laptop directly into your router or modem with an Ethernet cable and run a speed test — Speedtest.net by Ookla is the usual choice. Then run the same test over Wi-Fi, in the same spot, a minute later.
Compare the two numbers:
- Wired speed matches your plan, Wi-Fi is much slower: your NBN connection is fine. The problem is your home Wi-Fi — go to Step 4.
- Wired speed is also well below your plan: the problem is upstream — your line, your provider, or congestion. Skip to Steps 5 to 7.
- Both are fine right now: test again at 8pm. If the evening result collapses while the daytime result holds up, that points to peak-hour congestion (Step 6).
Run the test two or three times and note the date, time and result each time. If you end up complaining to your provider, those numbers are your evidence. A laptop without an Ethernet port needs a USB-C to Ethernet adapter — about $15 to $25 — and it is worth having in the drawer.
Step 3: Restart the modem and the NBN box, and check the cables
It sounds too simple, and that is exactly why it works so often. Turn off the modem/router and the NBN connection box (the white box NBN Co installed, sometimes called the NTD), leave them off for a full minute, then switch the NBN box back on first and wait for its lights to settle before switching the modem back on.
While you are there, check the cables. Push each one in firmly — a loose Ethernet lead or power cable can quietly cut your speed. Look for kinks, fraying or corrosion, and swap in a new Cat 6 Ethernet cable if anything looks damaged. They cost around $10. If your NBN box shows a red light that does not clear after a restart, that usually means a line fault — lodge it with your provider rather than keep rebooting.
Step 4: Fix the Wi-Fi, not the NBN
If your wired test was fine but Wi-Fi is slow, the NBN is doing its job and your home network is not. Work through these in order:
Move the router
Put it in a central spot, out in the open, at about shelf height — not on the floor, not in a cupboard, and not behind the TV. Brick walls, mirrors, fish tanks and large appliances all block Wi-Fi. Keep it away from microwaves, cordless phones and baby monitors, which interfere with the signal.
Split your Wi-Fi bands
Most routers broadcast two bands: 2.4GHz, which reaches further but is slower, and 5GHz, which is faster over short distances. If everything in the house is piled onto 2.4GHz — phones, TV, smart plugs, doorbell camera — it gets crowded. Put the things that need speed (laptop, TV, game console) on 5GHz and leave the smart-home gadgets on 2.4GHz.
Retire an old router
A router that came free with a plan three or four years ago often cannot keep up with a modern household. Older routers that only support Wi-Fi 4 or early Wi-Fi 5 struggle once you have fifteen or more connected devices, which is normal now with smart TVs, consoles, cameras and everyone’s phones. If your router is five years old and the Wi-Fi is slow in the back bedroom, a new router will usually do more than a faster plan. For bigger or oddly shaped houses, a mesh Wi-Fi system fixes dead zones more reliably than moving a single router around.
Update the firmware
Log into your router’s admin page (usually at an address like 192.168.0.1 or 10.0.0.1 — it is printed on the bottom of the router) and check for a firmware update. Old firmware can cause dropouts and slow speeds as well as security holes.
Step 5: Check what else is using the connection
Before blaming congestion, check whether something in your own house is eating the bandwidth. A game console downloading a 90GB update, a laptop running a Windows update, or a phone backing up photos to the cloud can all flatten the connection for everyone else — and they usually start by themselves.
Open your router’s connected-devices page, or check Task Manager (Windows) or Activity Monitor (Mac), and look for anything downloading heavily. Pause big downloads and cloud backups, or schedule them overnight, then test again. If the speed comes back, you have found your culprit.
Step 6: Test at different times of day
Evening congestion between about 7pm and 11pm is real. That is when the whole street is streaming, and the ACCC measures its broadband performance in exactly that window. If your wired speeds are fine at 2pm and poor at 8pm, day after day, that is a congestion pattern — and it points at your provider’s network capacity, not your house.
Keep a simple log for two or three days: a wired test at midday and another at 8pm. If the pattern holds, ring your provider with the numbers in hand and ask whether the problem is congestion on their side. If they cannot fix it, you are entitled to ask for a plan that matches the speed your line can actually deliver, a refund for the speed you did not receive, or to leave without an exit fee — the ACCC’s speed claims guidance says so.
Step 7: Know your connection type — and check for a free fibre upgrade
Not all NBN connections are equal. Fibre to the Premises (FTTP) runs fibre all the way into your house and supports every speed tier. Fibre to the Node (FTTN) relies on old copper phone lines for the last stretch to your house, and that copper is slower, more fault-prone, and can get worse after rain. Fibre to the Curb (FTTC) and HFC (cable) sit in between.
If you are on FTTN or FTTC, check whether your address is eligible for a free upgrade to full fibre. NBN Co has been running the upgrade program since 2020 and around two million homes have already been upgraded. The usual path is to order a higher-speed plan — usually NBN 100 or faster — from a participating provider, and NBN Co installs the fibre at no cost to you. Check your address on the NBN Co website to see what connection type you have and whether an upgrade is available: nbnco.com.au.
If your wired speed is poor at every hour of the day, on a wired connection, that combination usually means a line fault rather than congestion. Log it with your provider — NBN Co does not deal directly with residential customers, so your provider is the one who lodges the fault with NBN Co and books a technician if needed.
Step 8: When a faster plan helps — and when it does not
Upgrading your plan only helps if your wired test already reaches your current tier and you genuinely need more speed than that tier provides. A household of four streaming in 4K, gaming and video-calling at once will feel the difference between NBN 50 and NBN 100. A household whose wired speed already matches its plan but whose Wi-Fi dies in the back bedroom will not — the bottleneck is the router, not the plan.
As a rough guide: NBN 25 suits one or two light users, NBN 50 suits a small household streaming in HD, and NBN 100 suits a busy household with 4K streaming, gaming and video calls. Paying for NBN 250 or faster only makes sense on a full-fibre connection with a router that can actually deliver it.
Step 9: If your provider will not fix it, complain properly
If you have tested properly and the speed is still well below your plan, complain to your provider in writing — through their complaints form or by email — and keep a copy. Under the Telecommunications (Consumer Complaints Handling) Industry Standard, your provider must acknowledge your complaint within 2 working days and propose a fix within 10 working days.
In your complaint, include your wired test results with dates and times, your plan tier and its typical evening speed, and what you want: the fault fixed, a credit for the speed you did not receive, a move to a cheaper tier that matches what your line can deliver, or to leave without a fee. If the provider does not resolve it, escalate to the Telecommunications Industry Ombudsman (TIO) — the service is free for residential customers, and the TIO can make binding decisions up to $100,000. You can reach the TIO on 1800 062 058.
Frequently asked questions
Why is my NBN slow at night but fine during the day?
That is the classic congestion pattern. Between 7pm and 11pm the network is at its busiest, and if your provider has not bought enough capacity, speeds drop. Test wired at midday and again at 8pm for two or three days — if the daytime result is fine and the evening result is not, the problem is congestion, not your equipment.
Does weather affect NBN?
It can, mainly on FTTN connections that rely on old copper lines — heavy rain can make speeds drop or the connection drop out. Fixed wireless can also suffer in bad weather. Full fibre (FTTP) and HFC are barely affected unless a storm damages street equipment.
Will a faster NBN plan fix my slow Wi-Fi?
No. If your wired speed already matches your plan, the bottleneck is inside your house — router position, an old router, or too many devices on one band. Fix those first. A faster plan only helps when the wired connection itself is reaching the current plan’s limit and you need more.
What speed do I actually need?
For most households, NBN 50 covers HD streaming and everyday use, and NBN 100 covers 4K streaming, gaming and several people video-calling at once. What matters more than the headline number is whether you actually receive it — test wired, and compare against your plan’s typical evening speed.
Can I use mobile data as a backup while the NBN is down?
Yes — hotspotting from your phone works for emails and browsing, though it will chew through your allowance fast with video. Before relying on it, check how much mobile data you actually need so you do not burn through a month’s allowance in one afternoon.
