When one device is slow and everything else on the same network is fine, you can stop thinking about your broadband entirely. The fault is on that device, which is good news, because device-level Wi-Fi problems have a short list of causes and most are settings rather than hardware.
The short answer
Check which band the device joined, because a device stuck on 2.4 GHz will be a fraction of the speed of one on 5 GHz. Then turn off the adapter’s power saving, which throttles Wi-Fi to save battery and is enabled by default on most laptops. Update the adapter driver, and check that the device is not stuck on a distant mesh node or extender.
Confirm it really is one device
Run a speed test on the slow device and on a phone standing in exactly the same place at the same height. Same spot matters: comparing a laptop in the back bedroom against a phone next to the router tells you nothing. If the phone is dramatically faster in the same location, the device is the problem.
Check which band it is connected to
Look at the connection details. If the device is on 2.4 GHz while your phone is on 5 GHz, that alone explains the difference, and it is often a factor of five or more. Connect it explicitly to the 5 GHz network if the router broadcasts them separately.
Turn off adapter power saving
On Windows, open the adapter properties in Device Manager, go to the power management tab, and clear the option allowing the computer to turn off the device to save power. Then in advanced settings, look for a power saving mode and set it to maximum performance. This is the single most common cause of a slow laptop on fast Wi-Fi.
Set the power plan to high performance while plugged in
Balanced and power saver plans throttle the wireless adapter. If the device is fast on mains and slow on battery, this is exactly what is happening.
Update the wireless adapter driver
Get it from the laptop maker’s support page for your exact model rather than from Windows Update, which often ships a generic version. Wireless driver updates make a genuine difference to throughput.
Forget the network and rejoin
This clears a stale profile, including a stored preference for a band or an access point that is no longer the best choice.
Check whether it is stuck on an extender or distant node
Devices cling to a connection until it becomes unusable rather than switching to the best available. A laptop still attached to an extender in another room will be slow no matter how close you are to the router. Forget the extender network on that device.
Look for a VPN, proxy or filtering software
A VPN routes all traffic through another server and can halve throughput. Security software that inspects traffic does the same. Disable each temporarily and retest.
Test with an ethernet cable
If the device is fast on a cable and slow on Wi-Fi, the wireless adapter or its configuration is the fault. If it is slow on both, the problem is the device itself rather than its wireless.
Check what the connection is actually negotiating rather than what the device is capable of. On Windows, the network status shows a link speed. If a laptop that supports Wi-Fi 6 is negotiating at 72 Mbps, it has connected on 2.4 GHz with a single stream, and that is the number to fix.
Hardware limits worth knowing
- Older laptops with 2.4 GHz only adapters cannot exceed roughly 60 to 70 Mbps in practice, no matter how fast your broadband is.
- Single-antenna devices get roughly half the throughput of dual-antenna ones. Many budget laptops and most tablets have one.
- Metal laptop bodies place the antenna in the screen bezel, and a closed or angled lid affects reception.
- USB 3 devices generate interference in the 2.4 GHz band. An external drive plugged in next to a Wi-Fi dongle is a classic and baffling cause of slowness.
If you use a USB Wi-Fi adapter, plug it into a short extension cable rather than directly into the machine. Sitting it next to USB 3 ports and a hot chassis costs a surprising amount of performance, and moving it thirty centimetres away often doubles the speed.
When it is the device rather than the Wi-Fi
If the device is also slow on ethernet, the problem is not wireless at all. Look at whether the machine is short of memory, whether a background process is saturating the connection, or whether the browser is the bottleneck rather than the network. A speed test in a different browser, or from a different application, separates these quickly.
Also check for a stuck update or sync client. A machine quietly downloading a large update will feel slow at everything else while the connection itself is working perfectly.
Why is my laptop slower than my phone on the same Wi-Fi?
Usually the band it joined, or adapter power saving. Phones aggressively prefer 5 GHz and do not throttle their radios the way laptops on a balanced power plan do.
Does adapter power saving really make that much difference?
Yes, often halving throughput or worse, and it is enabled by default. It is the first thing to change on any laptop that is slow on Wi-Fi.
Why does my device stay connected to a distant access point?
Devices hold a connection until it becomes unusable rather than switching to the best available. Forgetting the network on that device, or using a mesh system that manages handover properly, resolves it.
Can a USB drive slow down Wi-Fi?
USB 3 devices emit interference in the 2.4 GHz band, and a drive or hub near a wireless adapter can noticeably reduce speed. Moving either one apart is a quick test.
Is it worth buying a USB Wi-Fi adapter for an old laptop?
Often, yes. A modern dual-band adapter is inexpensive and can transform an old machine with a 2.4 GHz only card. Use a short extension cable to keep it away from the chassis.
The bottom line
Compare the slow device against a phone in exactly the same spot, then check which band it joined and turn off adapter power saving. Those two account for most single-device slowness on laptops. If it is slow on ethernet too, stop looking at Wi-Fi and look at the machine.
