Fixing slow or patchy Wi-Fi

Most “slow internet” at home is slow Wi-Fi. Before changing provider or buying a new router, find out which one you have.

Is it the Wi-Fi or the line?

Run the speed test twice: once on a cable plugged into the router, or failing that right next to it, and once where the problem is. If the cable is fast and the far room is slow, the line is fine and the wireless is the problem. If both are slow, the problem is upstream — see a checking order for a bad connection.

Distance and obstacles

Wi-Fi weakens quickly through walls and floors, and some materials stop it almost entirely: concrete, brick, metal, mirrors, and water — including fish tanks and people. A router in a cupboard, behind a television or at the far end of the home loses much of its reach before it starts.

Put it in the open, high up, near the middle of where you use it. Moving it two metres often matters more than any setting.

The three bands

• 2.4 GHz reaches furthest and gets through walls best, but it is slow and crowded: neighbours, Bluetooth and microwave ovens share it.
• 5 GHz is much faster and less crowded, but has shorter reach.
• 6 GHz (Wi-Fi 6E and 7) is faster and emptier still, with the shortest reach, and needs devices that support it.

Most routers put all of them under one network name and move devices between them automatically. If a device keeps clinging to 2.4 GHz near the router, giving 5 GHz its own name for a test shows whether the band is the problem.

Channels and neighbours

In a block of flats, dozens of networks compete for the same channels. On 2.4 GHz only channels 1, 6 and 11 do not overlap, so a router on 3 or 9 interferes with two groups at once. Most routers pick a channel automatically; if yours has a fixed one, set it back to automatic or choose the least crowded. On 5 GHz, narrower channels (40 or 80 MHz rather than 160) are often more stable in a crowded building.

One router is not enough

For a large home or several floors, a single router will leave dead spots however it is set up.

• A mesh system — several units working as one network — covers a home evenly and moves devices between units.
• A wired access point in the far room is the most reliable fix if you can run a cable there.
• A basic range extender is the cheapest option but often halves speed, because it repeats everything over the same radio.

The device itself

• An old device (802.11n or earlier) is slow on its own, and can slow everyone else sharing the band.
• Forgetting the network and joining again clears a surprising number of problems.
• Update the operating system and Wi-Fi drivers, especially on Windows laptops.

Reading the signal

Signal strength is measured in dBm: around −50 is excellent, −67 is fine for calls and video, and below −75 things start to break up. Each system can show it:

netsh wlan show interfaces            # Windows: signal %, channel, receive rate
/System/Library/PrivateFrameworks/Apple80211.framework/Resources/airport -I
                                      # older macOS; on newer macOS, hold Option and click the Wi-Fi icon
iw dev wlan0 link                     # Linux

More commands like these are on the local checks page.

When to call the provider

When a cable at the router is slow too, when the speed collapses at the same time every evening, or when the router’s own status page shows the connection dropping. How to report a network problem covers what to send them.