Diagnosing Slow Internet

Slow internet can originate from several different layers — and misidentifying which one wastes hours of troubleshooting. Before you call your ISP or restart the router for the tenth time, spend 5 minutes with this systematic approach to find out exactly where the slowdown is.

Step 1 — Locate the Bottleneck

1

Run a Speed Test on This Computer

Go to fast.com or speedtest.net. Note the download, upload, and ping results.

2

Test Another Device on the Same Network

If a phone or another computer is fast, the problem is this specific PC. If everything is slow, the issue is the router or ISP.

3

Test with Ethernet vs. Wi-Fi

Plug directly into the router with an Ethernet cable. If wired is fast and Wi-Fi is slow, the issue is the Wi-Fi connection, not the internet line.

4

Compare to Your Plan Speed

Check what speed you're paying for. If wired speed matches your plan, the ISP line is fine. If wired is significantly slower, contact your ISP.

If the Problem Is This PC

Check for Background Bandwidth Usage

Open Task Manager (Ctrl+Shift+Esc) → Performance tab → Open Resource Monitor → Network tab. Look for processes uploading or downloading in the background. Common culprits: Windows Update, cloud backup (OneDrive, Dropbox, Backblaze), BitTorrent clients left running, and browser video preloading.

Update the Network Adapter Driver

An outdated Wi-Fi or Ethernet driver can significantly limit throughput. In Device Manager, expand "Network Adapters," right-click your adapter, and select Update driver. Better yet, download the latest driver directly from the laptop or motherboard manufacturer's website.

DNS Cache and Network Reset

Open Command Prompt as Administrator and run:

  • ipconfig /flushdns — clears cached DNS records
  • netsh winsock reset — resets the network stack
  • netsh int ip reset — resets TCP/IP settings

Restart after running these commands.

Switch to Faster DNS Servers

Your ISP's default DNS servers are often slower than alternatives. Try Cloudflare (1.1.1.1) or Google (8.8.8.8). On Windows: Network Settings → your adapter → Properties → IPv4 Properties → set Preferred DNS to 1.1.1.1, Alternate to 1.0.0.1.

If the Problem Is Wi-Fi

  • Distance and obstacles: Wi-Fi degrades rapidly with distance and through walls. Move closer to the router or invest in a Wi-Fi extender or mesh system.
  • Channel congestion: If neighbors are on the same Wi-Fi channel, interference slows everyone. Use a Wi-Fi analyzer app and switch your router to the least congested channel (1, 6, or 11 on 2.4GHz).
  • 2.4GHz vs 5GHz: Connect to the 5GHz band if you're within 30 feet of the router — it's significantly faster and less congested than 2.4GHz.
  • Restart the router: Power cycle the router and modem (unplug both for 30 seconds). This clears memory and re-establishes a clean connection to the ISP.

If It's Your ISP

If your wired speed test consistently shows speeds well below your plan (not just during peak evening hours, but throughout the day), the issue is on the ISP's side. Document your speed tests with timestamps and call to report the problem — ISPs often have deteriorating line equipment in your area that they'll fix, especially if multiple customers complain.

Modem age matters. If you rent or own a modem that's more than 3–4 years old, it may not support the higher speeds your ISP now offers. An old DOCSIS 3.0 modem can't get gigabit speeds even on a gigabit plan. Check your modem model against your ISP's approved device list.

Slow Internet and Malware

Malware that uses your machine for cryptocurrency mining, spam sending, or DDoS participation can consume significant bandwidth without any visible window. If your internet is slow specifically on this PC even while it's "idle" and other devices are fast, run Malwarebytes immediately.

We can diagnose it in-shop. If you've tried all the above and your connection is still slow only on your PC, bring it in. We'll determine whether it's a driver issue, malware, a hardware network adapter problem, or a configuration issue — and fix it.