Start by asking where the slowness is
“Slow Wi-Fi” is a feeling, not a diagnosis. The cause might be the wireless link, the router, the internet line, the website you are using, or the device in your hand. Narrowing it down first saves a lot of guesswork.
Some quick questions help:
- Is it slow on every device, or only one?
- Is it slow everywhere in the house, or only in some rooms?
- Is it slow all the time, or at certain times, such as evenings?
- Is it slow for every site or app, or only one service?
- Is a device connected by cable also slow?
A cabled device that is fast while Wi-Fi devices are slow points to the wireless link. If both are slow, look at the router, the line or the provider. Measuring speed consistently helps here.
Distance and obstacles
Wi-Fi signals weaken as they travel and are absorbed or reflected by what is in the way. Typically, the more walls and floors between a device and the router, the weaker the signal. Dense materials such as brick, concrete and plaster with metal mesh, as well as mirrors, large metal objects, water tanks and aquariums, tend to block more than ordinary wooden or plasterboard walls.
A weaker signal forces the connection to a lower speed and increases retransmissions, which also adds delay. A device that shows full bars may still have a modest connection, and one with fewer bars will often be noticeably worse.
Possible responses include moving the router to a more central, open and higher position (not inside a cupboard or behind a television), or adding coverage, which is the situation where a mesh system or a wired access point can help.
Interference
Wi-Fi shares radio frequencies with other things. The 2.4 GHz band in particular is used by many other devices, and can be disturbed by:
- neighbouring Wi-Fi networks;
- Bluetooth devices, cordless phones and baby monitors;
- microwave ovens in use nearby;
- some wireless cameras and similar gadgets.
The 5 GHz band is typically less crowded and offers more speed, but with shorter range and weaker penetration of walls. Newer equipment may also support 6 GHz, which has more room still but the shortest reach. Many routers can combine these bands under one name or separate them, and the device decides, or you choose, which to use.
Congestion
Congestion has two forms.
Neighbouring networks. In apartment buildings and dense streets, many networks compete for the same channels. Routers normally choose a channel automatically, though they do not always choose well. Some routers let you set a channel manually, and moving to a quieter one can help. This is a try-and-see adjustment.
Your own household. Every device shares the same radio airtime and your internet connection. Many devices doing heavy tasks, such as video streaming in several rooms, large cloud backups and game downloads, will compete. A device on a slow signal can also use more airtime to move the same data, which affects the others. Hence one badly placed gadget can slow nearby ones more than its own needs would suggest.
Cheap and older routers may also struggle to handle many simultaneous connections, particularly with dozens of smart home gadgets joined, a point linked to the internet of things in general.
Device limits
The weakest link often is the device. Older phones, laptops and smart TVs may support only older Wi-Fi generations and lower speeds, or only the 2.4 GHz band. Small gadgets often have tiny antennas and modest radios. A modern router does not make an old device faster, but the old device may also slow down others in some setups, because the router spends more airtime serving it.
Check the specifications of the device if available. And sometimes the slowness is not the radio at all: a device that is short on storage, busy with updates or running many apps may feel slow whatever the network does.
The router and the line
If everything is slow, including cabled devices, look at:
- Router overheating or age. Routers that are old, covered or hot can behave poorly. A restart often clears temporary faults, though a repeating problem suggests the router needs replacing.
- Out-of-date firmware, which can cause stability problems. Updating router firmware is worthwhile.
- The provider’s line. Faults, congestion at busy times, or a plan that is simply too small for the household. Contacting the provider, ideally with a few wired test results, is reasonable.
- DNS problems, which can make pages slow to start loading even when the connection is fine.
Software and background activity
Sometimes a program is using the connection without you noticing: operating system or app updates, cloud photo uploads, a backup running, or a family member’s download. Checking what is running on the device, and pausing large transfers, can quickly show if this is the cause.
A VPN can reduce speed too, since traffic takes a longer path and is encrypted. It is a trade-off for those who use one, not necessarily a fault.
A sensible order to try things
- Restart the router (and modem) and the affected device.
- Move closer to the router and see if speed improves. If it does, the problem is signal strength.
- Test a device by cable. If it is fast, the line is probably fine.
- Pause large downloads and streams to see if congestion is the cause.
- Try the 5 GHz band for devices that support it, where range allows.
- Check for router and device updates.
- Consider moving the router, changing its channel, or adding coverage with mesh or a wired access point.
- If a cabled test is also slow, contact the provider.
Change one thing at a time so you know what helped. Some causes will not be fully fixable, since a thick wall or a crowded building is hard to change, but understanding the cause usually points to a realistic remedy.