Is it the phone, the router or the line?
Slow WiFi is a chain problem. The phone talks to the router over radio, the router talks to your provider over the line, and the provider talks to the rest of the internet. Any link can be the slow one, and restarting the router only fixes one kind of fault. Ten minutes of testing tells you which link to work on.
Match the symptom to the likely cause
| Symptom | Likely cause | How to confirm |
|---|---|---|
| Slow on every device, everywhere in the home | The line or the provider | Test right next to the router, and on a second device |
| Slow in one room only | Weak signal | Check the signal level in that room |
| Slow mostly in the evening | Congestion, on the channel or at the provider | Test at different times, and look at neighbouring networks |
| Only this phone is slow | The phone: band, power saving, a VPN | Compare with another phone standing in the same spot |
| Speed test is fine but one app is slow | That service, or DNS | Try another app, or a different DNS |
| Connected, but pages sometimes stall | The router struggling, or DNS | Ping the router and a public server at the same time |
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The tests, in order
- Run a speed test beside the router, then where it is slow The difference between the two numbers is the coverage problem. The number beside the router is roughly what the line delivers.
- Look at the signal level and the band Many phones show signal strength and frequency in the WiFi network details, and an analyser app shows the exact level. Around minus 67 dBm or better is comfortable for calls and video; around minus 75 and below, expect trouble.
- Look at the channels around you An analyser shows neighbouring networks. On 2.4 GHz, channels 1, 6 and 11 do not overlap, so pick whichever of those is least crowded in the router settings.
- Ping the router and a public server together If the ping to the router jumps around, the problem is the WiFi. If only the ping to the internet is poor, it is the line or the provider.
- Switch off the VPN, Private DNS and data saver Then test again. Each of these can slow a connection that is otherwise fine.
- Open the router's app Check for a firmware update, see which devices are connected, and find the one downloading everything at once.
Apps for measuring
WiFiman. Free, from a networking equipment maker, with signal readings, speed tests and a scan of devices on your network.
WiFi Analyzer (open source). Channel graphs and signal levels, with no advertising. The clearest way to see a crowded channel.
WiFi Analyzer by olgor. The same job with a different layout and a signal meter that is handy for walking from room to room.
Speedtest by Ookla. The familiar speed test, with ping and jitter alongside the download and upload figures.
FAST. A one tap test against Netflix's servers, which tells you whether streaming specifically should work.
nPerf. Tests speed, browsing and streaming, and keeps a history so evenings and mornings can be compared.
Fing. Lists every device on the network, which is how an unknown device or a heavy downloader turns up.
PingTools. Ping, traceroute and other network utilities for the router test above.
Network Analyzer. Network scanning, ping and DNS lookups in one tidy app.
analiti. Detailed WiFi analysis with speed tests, for anyone who wants more numbers than the others provide.
1.1.1.1. Switches the phone to a fast public DNS resolver, a quick way to test whether slow lookups are the problem.
Router apps
TP-Link Tether. Settings, connected devices and firmware updates for TP-Link routers, without the web interface.
NETGEAR Nighthawk. The same for NETGEAR routers, including a built-in speed test.
eero. The only way to manage an eero mesh system, and a good view of which access point each device is using.
Google Home. Manages Google Wifi and Nest Wifi, alongside the rest of the smart home.
ASUS Router. Channel settings, connected devices and firmware for ASUS routers.
Fixes that work, and ones that do not
- Moving the router somewhere central and raised
- Using 5 GHz close by and 2.4 GHz for distance
- A mesh system or a wired access point for far rooms
- Updating the router firmware
- Moving off a crowded 2.4 GHz channel
- WiFi booster apps
- Clearing the phone's cache
- Task killer apps
- A faster broadband plan when the problem is coverage
- A repeater placed where the signal is already weak
Test beside the router, test where it is slow, look at the signal and the channels. Then fix the link that is actually slow.
Frequently asked questions
Why is my phone slower than my laptop on the same WiFi?
Different antennas and WiFi standards, a phone that has joined the 2.4 GHz band, or power saving on the phone. Test both side by side on the same band.
What is a good WiFi signal level?
Roughly, minus 50 to minus 60 dBm is excellent, around minus 67 is a common minimum for smooth calls and video, and below minus 75 things get unreliable.
Should I turn off MAC randomisation?
Android uses a randomised MAC address for each network by default. Switch to the device address only on your own home network, and only if the router's device filters or parental controls need it.
Is 5G on my phone the same as 5 GHz WiFi?
No. 5G is a mobile network generation. 5 GHz is a WiFi radio band. They are unrelated despite the similar name.
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