Troubleshooting

Troubleshooting slow internet speeds: Is it the ISP or your Router?

by RebootTips

My Internet’s Acting Up Again: Finding the Real Culprit for Slow Speeds

There’s nothing quite like that sinking feeling when you try to stream a movie, join a video call, or even just open a web page, and everything just… crawls. The little buffering spinner mocking you. Your spouse or kids start complaining, “The internet’s slow!” Your first instinct, like most people’s, is usually to point fingers at the ISP. “They’re throttling me,” or “Their service is just garbage.” I’ve been there, more times than I care to admit, both personally and professionally.

Why the Shotgun Approach Fails

The common approach usually goes something like this: restart the router, maybe the modem, and if that doesn’t work, spend an hour on the phone with ISP support, only for them to tell you to restart your router again. It’s frustrating, and often, it doesn’t solve anything because you haven’t actually identified the problem. Throwing a new router at it or swapping modems without understanding where the bottleneck truly lies is a waste of time and money. My method is about isolating the problem systematically, gathering real data, and then acting on it. It’s about getting past the guesswork and getting to the facts.

How to Pinpoint Your Slowdown

When I run into this, whether it’s at my own house or a client’s, I follow a pretty specific sequence. It gives me objective data, and frankly, it keeps the ISP support from pushing back when I call them with proof.

  1. Start with a Baseline Check: Before you touch anything, get a snapshot of your current performance.
    • Connect a computer directly to your router using a known good Ethernet cable. This avoids Wi-Fi variables.
    • Go to a reliable speed test site like speedtest.net or fast.com. I usually run both, maybe a few times, and note down the download, upload, and latency (ping) results. Take screenshots. This is your “before” picture.
    • Also, jot down your contracted speeds with your ISP. You need to know what you’re actually paying for.
  2. The Ol’ Power Cycle (The Universal Fix-All): It sounds cliché, but it works surprisingly often.
    • Unplug your ISP modem and your Wi-Fi router from power.
    • Wait about 30-60 seconds.
    • Plug the modem back in first. Let it fully boot up (all its lights should be solid, not blinking). This might take a few minutes.
    • Then, plug your Wi-Fi router back in. Let it boot up completely as well.
    • Once everything is powered on and stable, re-run your speed tests from step 1. If things are better, great! If not, proceed.
  3. Isolate the ISP Modem: This is the critical step. We need to take your router out of the equation entirely.
    • Locate your ISP modem. This is the box that converts the signal from your wall (coax, fiber, DSL) into Ethernet. Sometimes it’s a separate device, sometimes it’s combined with the Wi-Fi router. If it’s a combo unit, you’ll need to use a different approach later (or see if it has a “bridge mode”). For this guide, I’m assuming separate devices or a distinct modem port on a combo unit.
    • Disconnect the Ethernet cable that runs from your router’s WAN/Internet port to the modem’s LAN port.
    • Connect your test computer (the one you used in step 1) directly to the modem’s LAN port using that same Ethernet cable.
    • Now, here’s a crucial part many people miss: Reboot the modem again. Some modems “lock” to the MAC address of the first device connected to them. Plugging in a new device directly without a modem reboot often means it won’t get an IP address. I made this mistake once myself; spent a good 45 minutes scratching my head trying to figure out why my laptop wasn’t getting an IP from the modem. Just needed a power cycle.
    • Once the modem has fully rebooted and your computer has an IP address (check your network settings), run multiple speed tests again. Use the same sites and servers. Take screenshots.
  4. Analyze the Results:
    • Scenario A: Speeds are good (close to your contracted speeds) when directly connected to the modem. This tells you the problem is almost certainly with your router or your internal network.
    • Scenario B: Speeds are still slow (well below your contracted speeds) when directly connected to the modem. This strongly indicates the problem is with your ISP’s service or their modem itself.
  5. If the Router is the Culprit (Scenario A):
    • Reconnect your router to the modem.
    • Log into your router’s administration page (usually by typing 192.168.1.1 or 192.168.0.1 into a web browser). Check your router’s manual for the exact IP and default login.
    • Look for firmware updates. Outdated firmware can cause performance issues or introduce bugs. Download and install any available updates.
    • Check Wi-Fi settings: Are you on a crowded Wi-Fi channel? Tools like Wi-Fi Analyzer apps on your phone can help identify less congested channels, especially on the 2.4GHz band.
    • Review QoS (Quality of Service) settings. Sometimes these are misconfigured and prioritize certain traffic in a way that slows everything else down. Try disabling them temporarily for testing.
    • Consider how old your router is. Older routers might simply lack the processing power or Wi-Fi standards (like Wi-Fi 5 or Wi-Fi 6) to keep up with modern internet speeds or numerous devices.
    • If all else fails, a factory reset of the router can sometimes clear out corrupted settings. Just remember you’ll have to set it up from scratch afterwards.
  6. If the ISP is the Culprit (Scenario B):
    • Now you have data. Call your ISP’s technical support.
    • Explain that you’ve bypassed your router and connected a computer directly to their modem, and the speeds are still well below what you’re paying for.
    • Provide them with the specific speed test results (download, upload, ping) and the screenshots you took.
    • Ask them to check the signal levels to your modem and run diagnostics on their end. They might need to send a technician out or swap your modem. Being armed with data means they can’t just tell you “it’s your router” without further investigation.

Things people often get wrong

I’ve seen these pitfalls countless times, and usually, they just add to the frustration.

  • Relying solely on Wi-Fi for speed tests: Wi-Fi introduces too many variables: signal strength, interference from neighbors, walls, and even your microwave. Always, always use a wired connection for baseline testing. If your test computer only has Wi-Fi, you might need to borrow a friend’s laptop or get a USB Ethernet adapter.
  • Not distinguishing between modem and router: Especially with combo units, people often think the single box from the ISP is “the router.” It’s critical to know if it’s acting as a modem-only, a router-only, or both, and how to bypass the routing function.
  • Using an ancient Ethernet cable or a slow test device: Make sure your Ethernet cable is at least Cat5e. An old laptop with a slow network card or outdated drivers can itself be a bottleneck, giving you inaccurate low readings.
  • Only testing once: Network conditions fluctuate. Run several tests at different times of the day to get a more accurate average.

Systematic isolation and objective data are your best tools for diagnosing network speed issues, letting you confidently point the finger at the true culprit.

Related Posts