Slow internet feels like one problem. It is usually two, and they get fixed in completely different ways.

Your NBN connection is the service coming into your house. Your WiFi is how that service travels around inside your house. When people ring their provider about slow internet, most of the time the provider is delivering exactly what was ordered. The speed is being lost somewhere between the modem and the couch.

Working out which one you have takes about five minutes.

The quickest test: plug in a cable

Run a speed test on your phone in the room where the internet feels worst. Write the number down.

Now plug a laptop directly into the modem with an Ethernet cable and run the same test.

If the cabled result is close to what you pay for, your NBN connection is fine. The problem is your WiFi. If the cabled result is also slow, the problem is the connection coming into the house, and that is when you should look at NBN setup and troubleshooting or contact your provider.

This one test rules out half the possibilities and costs nothing.

Signs it is your WiFi

  • Speed is fine in one room and terrible in another
  • The connection drops when you walk upstairs or out the back
  • Video calls freeze but only in certain spots
  • Everything is fine at 10am and unusable at 7pm when the whole house is online
  • A device sitting next to the modem works perfectly

WiFi problems are almost always about distance, walls and how many devices are competing at once. Older homes with solid brick internal walls are particularly good at killing a signal, which is why the room at the back of the house is so often the worst one.

Read more on fixing WiFi dead zones if this sounds like your place.

Signs it is your NBN connection

  • Slow everywhere, including plugged in directly
  • The modem lights are not what they should be
  • The connection drops out entirely rather than just slowing down
  • It started suddenly and nothing in the house changed
  • Neighbours are having the same problem at the same time

These are carrier-side issues. Your provider needs to look at the line, and no amount of new equipment inside the house will fix it.

Worth knowing: not all NBN connections are equal. A fibre connection and a fixed wireless connection behave very differently under load, and that is set by the infrastructure at your address, not by what you are paying.

The third possibility nobody mentions

Sometimes both are working and the modem is the weak link.

The modem your provider posted out is built to a price. It is designed to cover an average apartment, not a two-storey house with brick walls, forty connected devices and someone working from the back bedroom. It does the job it was designed for and then quietly falls over when you ask for more.

This is the most common situation we see. The line is fine. The WiFi coverage is the problem. The equipment was never going to reach.

What to do next

If the cabled speed test came back fine, the fix is inside your house. Depending on the layout that might mean better placement, whole-home WiFi, additional access points, or running data cabling so the signal starts closer to where you actually use it. There is no single answer, because the right fix depends on the size of the house, what the walls are made of, and where the modem currently sits.

If the cabled speed test came back slow, ring your provider first. There is no point paying anyone to improve coverage of a connection that is not delivering.

We are also an internet plan reseller, so if your current plan or connection type is genuinely the limitation, we can set you up with an NBN or internet plan directly rather than sending you back around the loop.

Either way, start with the cable test. It is the fastest way to stop guessing.

Written by Yariv, Owner and Lead Installer at AVsion. 14 years installing AV, WiFi and security systems across Sydney’s eastern suburbs. ACRS Master Cabler A036841.

Frequently asked questions

How do I know if my internet problem is the NBN or my WiFi?

Plug a laptop directly into your modem with an Ethernet cable and run a speed test. If the cabled speed is close to what you pay for, your NBN connection is working and the problem is your WiFi coverage inside the house. If the cabled speed is also slow, the issue is with the connection coming into your property and your internet provider needs to investigate. This single test separates the two problems and takes about five minutes.

Why is my WiFi slow in only one room?

That is a coverage problem, not a speed problem. WiFi signal weakens as it travels through walls, floors and furniture, and solid brick or double brick construction blocks it far more than plasterboard. If one room is consistently worse than the rest of the house, the signal is arriving there too weak to be useful. The fix is usually additional access points or cabling that moves the signal source closer to that part of the home.

Can AVsion fix a problem with my NBN connection itself?

If the fault is on the network side, that sits with your internet provider and the network operator. What we can do is diagnose whether the problem is actually the connection or the setup inside your home, sort out modem and router configuration, and fix coverage issues. We are also an internet plan reseller, so if your plan or connection type is the limitation, we can arrange an NBN or internet plan for you directly.

Will a new modem fix my slow WiFi?

Sometimes, but not always. A better modem or router helps if the existing one is old, underpowered or badly placed. It will not help if the house is simply too large or too solidly built for one device to cover. In many homes the real answer is more than one signal source, properly positioned and ideally wired back to the modem. We assess the home first rather than assuming new equipment is the answer.

Why is my internet fine during the day and slow at night?

Evening slowdowns usually come from congestion, either on your provider’s network at peak times or inside your own home as more devices come online. If a cabled speed test is also slow in the evening, it is network congestion and worth raising with your provider. If cabled speeds hold up but WiFi struggles, your home network is being asked to handle more devices than it was set up for.

Do I need data cabling or is wireless enough?

It depends on the home. Wireless is enough in smaller homes with open layouts and lighter construction. Larger homes, two storey homes and older brick homes usually perform far better with cabling running to one or two additional access points, because each one then starts with a full strength connection instead of relaying a weak one. We look at the layout and construction before recommending either.