Networking, Wi-Fi & Fibre Optics
Slow Wi-Fi is rarely one fault. It is usually distance, thick walls, a crowded channel or simply the internet plan. One wired test tells you which half of the problem you have, and the ten causes below cover almost everything else.
What you will learn
Applies to
Tools Required
Before you start
Important
Step-by-Step Guide
1 / 8 steps
Step 1
Test on a cable first
Plug a laptop into the router with Ethernet and run a speed test.
Expected result: If the cable is slow too, the problem is the internet plan or router, not Wi-Fi.
Repeat the test on Wi-Fi a few metres from the router, then in the slow room.
Expected result: Fast near the router but slow far away means a coverage problem.
Take the router out of cupboards and off the floor. Place it high, in the open, near the middle of where people use Wi-Fi.
Expected result: Signal reaches more rooms with fewer walls in the way.
Thick coral-stone and concrete walls stop a lot of signal. If the slow room is behind them, plan an access point on that side.
Expected result: You know whether placement alone can fix it.
Connect phones and laptops to the 5 GHz network when close enough, and keep 2.4 GHz for far rooms and older devices.
Expected result: Nearby devices get faster, less crowded connections.
On 2.4 GHz choose the least busy of channels 1, 6 or 11 at 20 MHz. On 5 GHz use 40 or 80 MHz where few networks are nearby.
Expected result: Less waiting for airtime shared with neighbours.
Menu names differ by router brand.
Use the router's update page or app to check for firmware, and keep the power on until it finishes.
Expected result: Known bugs and security issues are fixed.
Download firmware only from the manufacturer.
If rooms are still slow, add access points cabled back to a switch, close to where people are, instead of extenders at the edge.
Expected result: Each area has a strong signal and fewer devices per access point.
Interactive Demonstration
What is slow?
Is a laptop on an Ethernet cable to the router fast?
If not, the likely cause
The internet connection or the router itself is the bottleneck, not Wi-Fi.
What to do: Restart the router and ISP device once. If the cable test stays slow, contact your ISP with the results and check nothing is running large uploads or backups.
Is Wi-Fi fast when standing next to the router?
If not, the likely cause
Router configuration or interference: legacy modes, a crowded channel or nearby interference sources.
What to do: Use WPA2/WPA3 with AES, turn off b/g-only modes, choose channel 1, 6 or 11 at 20 MHz on 2.4 GHz, and use 5 GHz where possible.
Is the router's firmware up to date?
If not, the likely cause
Old firmware can carry bugs that affect performance and security.
What to do: Update from the router's update page or app, and keep power on until it finishes.
Every check passed
The router may be too small for the building or the number of users.
What to do: Plan cabled access points. Try the coverage simulator on this page, then ask for a site survey.
Is the router high, in the open and roughly central?
If not, the likely cause
Poor router placement.
What to do: Move it out of cupboards and off the floor, towards the middle of the building.
Is the slow room free of thick stone or concrete walls between it and the router?
If not, the likely cause
Physical obstructions are absorbing the signal.
What to do: Add a cabled access point on the far side of the wall. See the Wi-Fi dead zones guide.
If you use extenders, are they placed halfway rather than at the weak edge?
If not, the likely cause
An extender at the edge repeats a weak signal and cuts speed.
What to do: Move it closer to the router, or replace it with a cabled access point.
Every check passed
The area needs its own access point.
What to do: Use the coverage simulator to see where an access point would help, then cable one in.
Is a wired test at the busy time as fast as in the morning?
If not, the likely cause
The internet plan or the ISP's network is congested at peak times.
What to do: Check what is using bandwidth (backups, updates, CCTV uploads) and discuss the plan with your ISP.
Are only a few devices connected at the busy time?
If not, the likely cause
Too many devices sharing one access point's airtime.
What to do: Add access points so each serves fewer people, and move capable devices to 5 GHz.
Is your 2.4 GHz channel clear of many neighbouring networks?
If not, the likely cause
Channel congestion from nearby networks.
What to do: Choose the least busy of channels 1, 6 or 11 at 20 MHz, and prefer 5 GHz.
Every check passed
Capacity planning for the building may be needed.
What to do: Ask for a site survey that counts users per area and plans access points for peak use.
Does the router keep running through short power dips?
If not, the likely cause
Power cuts or voltage drops restart the router.
What to do: Put the router, ISP device and switch on a UPS.
Does it keep working when the microwave or other appliances are on?
If not, the likely cause
Interference on 2.4 GHz.
What to do: Move the router away from the appliance and connect devices to 5 GHz.
Is the router cool and well ventilated?
If not, the likely cause
Overheating can make routers restart or drop connections.
What to do: Move it out of enclosed spaces and away from direct sun.
Every check passed
A failing router, firmware bug or ISP line fault.
What to do: Update firmware, note when drops happen, and ask your ISP to check the line. Replace the router if it keeps restarting.
Is the device connected to the right network and band, not a far extender?
If not, the likely cause
The device is holding on to a weak connection.
What to do: Forget the network and reconnect near the router, or select the 5 GHz network.
Are the device's software and Wi-Fi drivers up to date?
If not, the likely cause
Old drivers or software can limit Wi-Fi performance.
What to do: Update the operating system and Wi-Fi drivers, then restart the device.
Every check passed
The device's Wi-Fi hardware may be old or limited.
What to do: Compare with another device in the same spot. An old device may only support slower Wi-Fi standards.
Choose a building, then tap the plan to place up to four access points. Thick coral-stone and concrete walls weaken the signal far more than partitions. This is a simplified teaching model; real coverage needs a site survey.
No access points yet: tap the plan to place one.
Troubleshooting
Likely cause Internet plan, ISP fault or the router itself.
Solution Restart once, then contact the ISP with wired speed test results.
Likely cause Distance, placement or walls.
Solution Move the router high and central, or add a cabled access point.
Likely cause Coral-stone or concrete walls absorbing the signal.
Solution Put an access point on that side of the wall. See the Wi-Fi dead zones guide.
Likely cause Peak-time congestion on the ISP network or the Wi-Fi channel.
Solution Compare wired tests morning and evening. Change channel and use 5 GHz.
Likely cause Interference on 2.4 GHz.
Solution Use 5 GHz and move the router away from the kitchen.
Likely cause Too many devices on one access point.
Solution Add access points so each serves fewer users.
Likely cause Extender placed at the weak edge, repeating on the same radio.
Solution Move it halfway, or replace it with a cabled access point or mesh system.
Likely cause Legacy modes or old security (b/g-only, WEP or TKIP) enabled.
Solution Use WPA2 or WPA3 with AES and turn off legacy-only modes.
Likely cause Old firmware, overheating or power problems.
Solution Update firmware, improve ventilation and add a UPS.
In Depth
Slow Wi-Fi is rarely one fault. It is usually distance, thick walls, a crowded channel or simply the internet plan. One wired test tells you which half of the problem you have, and the ten causes below cover almost everything else.
Plug a laptop into the router with an Ethernet cable and run a speed test, then run the same test on Wi-Fi standing next to the router, then in the slow room. TP-Link's own testing guide uses the same wired-versus-wireless comparison.
Expect Wi-Fi to be slower than the cable even in the best case. The "link speed" a phone shows is a radio rate, and real throughput is always well below it.
A router in a cupboard, behind the TV or on the floor at one end of the building wastes much of its signal. Put it high, in the open and as central to the users as the cabling allows. TP-Link also advises against sitting directly underneath or above an access point, where the signal is weakest.
Walls and ceilings absorb Wi-Fi, metal and water most of all. In Zanzibar this matters more than the box suggests: thick coral-stone walls in Stone Town houses, reinforced concrete slabs, and metal roofs and security grilles can cut a signal sharply in one or two rooms. No router setting fixes a wall; a second access point on the far side does. See Wi-Fi dead zones in buildings.
Microwave ovens, Bluetooth devices, cordless phones, some baby monitors and electric motors all use or disturb the 2.4 GHz band. If Wi-Fi slows when the kitchen microwave runs, that is interference. Move the router away from them or use 5 GHz.
Every nearby network on the same channel takes turns with yours. In apartment blocks, hotels and busy streets, 2.4 GHz is often full. On 2.4 GHz use only channel 1, 6 or 11 at 20 MHz, because other channels overlap. On 5 GHz there are many more channels; DFS channels can be quieter but the router must move off them if it detects radar.
| Band | Strengths | Weaknesses |
|---|---|---|
| 2.4 GHz | Longest range, best through walls, every device supports it | Few non-overlapping channels, crowded, more interference, lowest speeds |
| 5 GHz | Many more channels, much faster, less interference | Shorter range, weaker through walls |
| 6 GHz | Wide, clean channels on Wi-Fi 6E and Wi-Fi 7 equipment | Shortest range, needs a 6 GHz capable device and router, and only where national rules permit it |
Let phones and laptops use 5 GHz where they can and keep 2.4 GHz for range and older devices. In Tanzania the position is not yet clear. TCRA's 2024 short range device specification lists 5945 to 6425 MHz for low-power 6 GHz Wi-Fi, but TCRA's July 2025 Wi-Fi band plan lists only 2.4 GHz and 5 GHz as licence-exempt bands, and the Wi-Fi Alliance's list of 6 GHz countries does not include Tanzania. Check with TCRA before buying equipment for 6 GHz.
Every phone, TV, camera and tablet shares the same airtime. A single home router may cope with a family, but not with a guesthouse full of guests streaming at once. Newer standards (Wi-Fi 6 and later) handle many devices better, but the lasting fix is more access points, each serving fewer people.
Router and access point updates fix bugs, security holes and sometimes performance. Check the manufacturer's update page or the router's update button a few times a year, and never cut power during an update. Old phones and laptops also benefit from updated Wi-Fi drivers.
Adding access points helps only if they are in the right places. Extenders plugged in at the edge of coverage repeat a weak signal and can halve speed. Access points cabled back to a switch, mounted on ceilings near where people are, work far better. See mesh Wi-Fi vs managed access points.
If the wired test is slow too, the internet plan is the bottleneck. A plan shared between many users, cloud backups, CCTV uploads or software updates running in the background can use most of it. Check usage at busy times and ask the ISP what speed is actually delivered.
Common mistakes include very wide channels on a crowded 2.4 GHz band, legacy modes (802.11b/g only, or old WEP and TKIP security) that force the network down to old speeds, two access points on the same channel side by side, and transmit power turned to maximum on every unit. Use WPA2 or WPA3 with AES, 20 MHz on 2.4 GHz, and 40 or 80 MHz on 5 GHz where the area is quiet.
Tip Try the coverage simulator on this page. Place access points on a simple floor plan and see where strong, moderate, weak and dead zones fall before you buy anything.
Note A speed test on a phone measures that phone, at that spot, at that moment. Test a few times, in the same places, before and after each change.
If several rooms are weak, guests or staff complain at busy times, or the building has thick stone or concrete walls, a short site survey and properly placed cabled access points usually solve it for good. See our networking, Wi-Fi and cabling service or contact us.
This guide is general information. Procedures, product features and firmware change, so check your own equipment's documentation before you start.
FAQs
Usually because everyone is online at once: neighbours on the same channel, family streaming, or the ISP's network busy in the evening. Compare a wired test at night with one in the morning to see whether it is the plan or the Wi-Fi.
No. 5 GHz is faster and less crowded but does not travel as far or through walls as well. In a far room behind thick walls, 2.4 GHz may be the more reliable connection.
Only if the router is the problem. A new router in the same cupboard behind the same stone walls gives the same weak signal. Placement and an extra cabled access point usually do more.
Sometimes, in a home, if placed halfway rather than at the edge of coverage. Many extenders repeat on the same radio, which cuts speed. For businesses, cabled access points are the better fix.
It depends on the router, the standard and what the devices are doing. If speed drops as people arrive, you need more access points rather than a faster internet plan alone.
A restart can clear a stuck router, but if you need one every day there is a fault to find: overheating, old firmware or a failing power supply. Keep the router in a ventilated place and on a UPS if power is unstable.
Yes, if they are on the same or an overlapping channel. Choose the least busy of channels 1, 6 or 11 on 2.4 GHz, or move devices to 5 GHz.
We measure the building, place access points where the signal is needed and wire them properly, so the Wi-Fi works in every room.
Ask for clarification, tell us a problem this did not solve, or suggest a topic. An engineer reads every message, and we use them to improve the Knowledge Center.
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