"The WiFi is slow" can mean a dozen different problems, and only some of them are wireless. The quickest route to a fix is to narrow it down in order: is it the internet, the wired network, one device, one area, or one time of day? Once you know which, the cause is usually clear.
Start with the facts
Before changing anything, gather facts. Vague complaints lead to random fixes.
- Where does it happen: everywhere, one floor, one room, one corner?
- When: all day, at peak times, at certain hours?
- Which devices: everyone, one model of laptop, phones only, scanners?
- Which applications: video calls, file transfers, a cloud system, everything?
- What does "slow" mean: pages loading slowly, calls freezing, disconnections, failure to connect?
- Did anything change recently: new equipment, renovations, new tenants, software updates?
Work from the outside in
With the facts in hand, check each layer in turn, starting with the parts that are quickest to rule out.
1. Rule out the internet connection
If everything is slow everywhere, including on wired computers, the problem is probably upstream of the WiFi. Check the internet connection's usage during the slow periods. A saturated connection, a failing firewall or a problem at the provider will look exactly like bad WiFi to users.
Test from a wired computer and from a wireless device standing near an access point. If both are slow, look at the internet link and firewall first.
2. Check the wired side of the access points
An access point is only as good as its connection back to the network. Common culprits include:
- An access point connected at 100 Mb/s instead of 1 Gb/s or faster because of a damaged or poorly terminated cable.
- Not enough Power over Ethernet, causing an access point to disable radios or features. See Power over Ethernet (PoE).
- Overloaded switch uplinks or misconfigured VLANs.
Your controller or management system will usually show link speed and power status for each access point.
3. Look at one device versus many
If only certain devices struggle, the cause is often on the device: outdated wireless drivers, aggressive power-saving settings, an old device that only supports slower standards, or a device that clings to a distant access point instead of roaming. Updating drivers and checking settings is cheap and often effective.
Older devices can also slow everyone else down. A device that connects at a low data rate uses much more airtime to send the same data, which leaves less for others on that channel.
4. Check coverage and signal quality in the problem area
If problems are tied to particular areas, measure the signal there. Check both signal strength and signal-to-noise ratio (SNR). Weak signal, low SNR or a lack of a second access point for roaming all point to coverage or placement problems. RSSI, SNR and signal strength explains what the numbers mean.
Look for physical changes too: new walls, relocated shelving, a metal partition or a ceiling renovation that moved an access point.
5. Look for interference and overlap
If signal is strong but performance is still poor, the usual suspect is interference, most often co-channel interference from your own access points or neighbours' networks. Too much transmit power, too many access points on the same channel, or channels set too wide for the environment all reduce capacity. Non-WiFi sources such as microwave ovens or wireless cameras can also be the cause. See Common sources of WiFi interference.
6. Check capacity at busy times
If the WiFi is fine early in the morning and slow by mid-morning, the network may simply be running out of capacity. Check how many clients each access point serves at peak, and how busy each channel is. Meeting rooms, training rooms, cafeterias and lobbies are frequent hot spots. The fix is usually more capacity where people gather, not more coverage. High-density WiFi design covers how.
Change one thing at a time. Adjusting power, channels and settings all at once makes it impossible to tell what helped. Make one change, measure, and record the result.
Common quick fixes that backfire
- Turning every access point to maximum power, which increases overlap and makes devices cling to distant access points.
- Adding access points without a plan, which can add co-channel interference rather than capacity.
- Using the widest channels everywhere, which reduces the number of independent channels available.
- Buying a faster internet connection when the bottleneck is the wireless network.
How ehZee can help
When the cause is not obvious, a survey finds it. Our WiFi surveys service measures coverage, SNR, channel overlap and interference with AirMagnet Survey Pro, and checks cabling, installation and security as part of our checklist. You get a clear explanation of why the network is slow and a ranked list of what to fix.
Common questions
Why is WiFi slow even with full bars?
Bars show signal strength, not capacity or interference. Co-channel interference, too many users, slow legacy devices or an overloaded internet connection can all cause slowness with full bars.
Will a new access point model fix it?
Only if the old equipment is the actual bottleneck. Placement, channel planning and capacity problems carry over to new hardware unless they are addressed in the design.
Should we restart the access points?
A restart can clear a temporary fault, but if problems return, there is an underlying cause worth finding.