Slow Internet? Here's How to Test, Diagnose and Actually Fix It

Slow internet is frustrating, but "slow internet" could mean your ISP, your modem, your router, your Wi-Fi, your device, or a specific website. Working through these systematically points to the real problem.

Step 1: What Speed Should You Get?

Check your NBN plan speed. Your ISP should provide typical evening speeds on their website. A 100Mbps plan typically delivers 90Mbps in testing; if you're getting 10Mbps, there's a problem. Note that wireless speeds are always lower than your plan speed due to overhead and signal quality.

Step 2: Test on Ethernet vs Wi-Fi

Connect a laptop to the router with an ethernet cable. Run speedtest.net. Then test on Wi-Fi in the same room. Compare results. If ethernet is fast but Wi-Fi is slow, the problem is your wireless network — not the internet connection. If ethernet is also slow, the issue is the NBN connection or your plan.

Step 3: Test at Different Times

Internet speeds drop during peak hours (6pm–10pm) when congestion is highest, particularly on HFC NBN connections. If speeds are fine in the morning but poor in the evenings, congestion is the cause. This is an ISP/NBN Co problem — you can ask your ISP to investigate or consider changing to a less congested RSP.

Step 4: Check the Router Logs

Log into your router admin panel and look at the connection statistics. High error rates on the DSL connection indicate line quality problems between your home and the node. This is something your ISP needs to investigate with NBN Co.

Step 5: Test Multiple Devices

If one device is slow and others are fast, the problem is that device — not the network. Check for background downloads, update processes or malware consuming bandwidth on the slow device.

Step 6: Check for Background Downloads

Windows Update, Steam, cloud backups and streaming services can silently consume all available bandwidth. Open Task Manager → Performance → Open Resource Monitor → Network tab to see what's using your connection.

When to Call Your ISP

If ethernet speeds are consistently 30%+ below your plan speed during off-peak hours, call your ISP and ask for a line speed investigation. Document your test results with times and dates before calling — it makes the conversation more productive.