How to Test Internet Speed and Resolve Lag Issues

An internet speed test is the fastest way to check whether your home connection is performing close to the plan you pay for. It can also help you work out whether the problem is your provider, your NBN technology, your Wi-Fi setup, or congestion inside your home.

That matters because a slow download result is not the same thing as lag. Some households have enough download speed for streaming but still get poor gaming, video call delays or unstable Wi-Fi in certain rooms. A proper internet speed test should check download speed, upload speed and latency, then be paired with a few basic troubleshooting steps.

If you want to test your line straight away, use the CompareUs internet speed test calculator and then compare the result against the guidance below.

Quick answer: how to use an internet speed test

Run your internet speed test over Ethernet first if possible, then repeat it over Wi-Fi in the rooms where you actually use the internet. Test at different times of day, especially during evening busy hours, and compare the result with your plan speed, your provider's typical evening speed guidance and the performance limits of your home equipment.

What an internet speed test actually measures

A standard internet speed test usually gives you three core numbers.

• download speed, which affects streaming, browsing and most everyday use;
• upload speed, which matters for video calls, cloud backups, gaming uploads and sending large files;
• latency or ping, which measures delay and matters most for gaming, video calls and other real-time activity.

Some speed tests also show jitter, which reflects variation in latency over time. High jitter can feel like unstable lag even when headline download speed looks acceptable.

Why your speed test result can be misleading

An internet speed test is useful, but only if you run it under sensible conditions.

If several people are streaming, downloading or gaming at the same time, your result may reflect household demand rather than the full capability of the service. NBN also warns that speed results can be affected by your broadband plan, Wi-Fi interference, the number of devices using the connection and busy-hour congestion, typically between 7pm and 11pm.

That means a single speed test should never be your only evidence. Use repeated tests and compare patterns.

How to run an internet speed test properly

Start with a controlled test.

1. Pause large downloads, cloud backups and software updates.
2. Disconnect or stop heavy use on other devices if possible.
3. Run one test over Ethernet directly from the modem or router.
4. Run another test over Wi-Fi in the room where performance feels poor.
5. Repeat the test at least a few times during the day and again during evening busy hours.
6. Record download speed, upload speed and latency each time.

If your Ethernet result is good but your Wi-Fi result is much worse, your main issue is probably in-home wireless performance rather than the broadband service itself.

What counts as a good result in Australia

The ACCC's Measuring Broadband Australia program provides an independent benchmark for how fixed-line and fixed wireless services perform in real homes. In its April 2026 update, the ACCC said most households were receiving speeds close to those promised on their NBN plans, although some problematic higher-speed and fibre to the node services were still underperforming.

This is why you should compare your result against the speed tier you actually bought rather than against a generic idea of fast internet. A household on a 25 Mbps plan should not expect the same result as a household on a 100 Mbps or 500 Mbps plan.

As a practical rule:

• if your result is broadly close to your plan speed over Ethernet, the line may be fine;
• if your result falls well short mainly on Wi-Fi, your home setup may be the problem;
• if performance drops mainly during busy hours, congestion or plan design may be involved;
• if latency is high while download speed looks acceptable, the issue may be lag rather than raw speed.

What causes lag even when speed looks fine

Lag is usually driven by delay, instability or contention, not just low download speed.

Common causes include:

• high latency;
• unstable Wi-Fi coverage;
• old routers that cannot keep up with newer speed tiers;
• too many active devices using the network at once;
• interference from walls, distance or poor router placement;
• provider congestion or limitations on a particular access technology.

NBN's recent guidance on home Wi-Fi says many customers still have routers that are too old, badly placed or poorly matched to newer speed tiers. NBN also notes that older Wi-Fi standards can cap real performance even when the underlying broadband plan is faster.

The simplest fixes for internet lag at home

Before changing provider, work through the basics.

Move the router

Put the router in a more central, open position rather than behind furniture or in a far corner of the house. NBN's Wi-Fi guidance says poor placement remains one of the most common causes of weak home performance.

Test Ethernet versus Wi-Fi

If Ethernet performs much better than Wi-Fi, focus on wireless improvement first. That may mean changing placement, upgrading the router or adding mesh Wi-Fi or an extender where appropriate.

Check the age of your router

A router that is several years old may not deliver the speeds available on newer broadband plans. This matters more now that higher NBN speed tiers became more widely available after the September 2025 wholesale speed changes on eligible FTTP and HFC services.

Reduce simultaneous heavy usage

Streaming on multiple screens, game downloads, cloud sync and video calls can all compete for bandwidth at the same time. Try running a speed test when the house is quieter and compare it with peak usage periods.

Restart equipment and update firmware

This will not solve every problem, but it is still worth doing when lag appears suddenly or after a long period without maintenance.

When the problem is your plan rather than your setup

Sometimes the internet speed test is telling you the household has outgrown the plan.

If your line and Wi-Fi setup are working reasonably well but several people regularly stream, game, work from home and make video calls at once, moving from a lower tier to a higher one may be more effective than endless troubleshooting. NBN's consumer guidance makes the same point: your experience depends not just on technology, but also on the chosen speed plan and how your provider configures the service.

When the problem is the connection technology

Your NBN technology can also limit the result. ACCC reporting and NBN guidance both note that performance varies across access types and household conditions. Fibre to the node can be more variable than FTTP or HFC for some users, and fixed wireless performance can vary more during busy periods or under local conditions.

If your results are consistently poor despite a good home setup, your access technology may be part of the explanation.

When to contact your provider

Contact your provider when:

• Ethernet results are consistently well below your plan expectation;
• speed collapses at the same times every day;
• latency spikes make gaming or calls unusable;
• dropouts accompany slow speeds;
• you suspect a line fault, modem fault or configuration problem.

Have your recent internet speed test results ready, including the times you ran them and whether they were over Ethernet or Wi-Fi. That gives the provider something concrete to work with.

How CompareUs can help after the speed test

If repeated internet speed test results show your current service is not the right fit, the next step is to compare available plans against your actual household needs. Use the CompareUs internet comparison hub, the internet value calculator, and the NBN speed calculator to work out whether a different plan or provider may suit you better.

Sources and methodology

This guide was prepared using current ACCC broadband performance reporting and current NBN consumer guidance on speed plans and home Wi-Fi setup. It is designed as a practical consumer explainer rather than a promise that any single speed test result will diagnose every broadband issue. Final troubleshooting should always be based on your plan, your equipment, your access technology and the latest advice from your provider.