Networking, Wi-Fi & Fibre Optics
Wi-Fi dead zones happen when walls, distance or a badly placed router stop the signal reaching a room. Map them with a phone, rule out cheap fixes, then add access points closer to the users, wired back to the network wherever you can.
What you will learn
Applies to
Tools Required
Before you start
Important
Step-by-Step Guide
1 / 8 steps
Step 1
Measure signal in every room
Walk the building with a Wi-Fi analyser app. Note the dBm reading and a speed test where people actually sit.
Expected result: You have a map of good, weak and dead rooms. Weaker than about -75 dBm is poor.
Mark thick stone walls, concrete slabs and metal on the plan between the router and the weak rooms.
Expected result: The pattern shows whether distance or a specific wall is the problem.
Place the router high and central, out of cabinets. On 2.4 GHz use channel 1, 6 or 11 at 20 MHz.
Expected result: Small homes and offices often improve. Large buildings need more access points.
Menu names vary by router.
A single-radio extender receives and resends on the same channel, so the airtime is shared.
Expected result: Devices on the extender get roughly half the speed, or less behind a thick wall.
If a network cable can reach a mesh unit, use it as wired backhaul instead of the wireless hop.
Expected result: The unit gets the full connection back to the router, through any wall.
In larger buildings, mount access points near users and run one cable to each from a PoE switch.
Expected result: Each access point has its own wired path, so speed holds up in every room.
In the controller, lower transmit power and plan channels so neighbouring access points differ.
Expected result: Phones move to the nearest access point instead of clinging to a far one.
Names vary by controller.
Put the router and PoE switch on a UPS. Every access point powered from the switch stays on too.
Expected result: Wi-Fi survives short cuts and the generator start-up without rebooting.
Interactive Demonstration
What best describes your Wi-Fi problem?
Is the router high, central and out of any cabinet?
If not, the likely cause
The router position is blocking or wasting the signal.
What to do: Move it high and central, away from metal, then measure again.
Is there only light wall between the router and the dead room?
If not, the likely cause
Thick stone or concrete walls are absorbing the signal.
What to do: Add an access point on the far side of the wall, wired back to the network.
Is the dead room within about two rooms of the router?
If not, the likely cause
One router cannot cover this distance.
What to do: Add wired access points, or a mesh unit with a cable to it.
Every check passed
Interference or a faulty radio is possible.
What to do: Check channels with an analyser app, restart the router, and ask a professional for a survey.
Is the internet speed fine when tested by cable at the router?
If not, the likely cause
The internet connection itself is slow.
What to do: Contact your ISP, or read our guide on why Wi-Fi is slow.
Is your network on a less crowded channel than the neighbours?
If not, the likely cause
Channel congestion.
What to do: On 2.4 GHz use channel 1, 6 or 11 at 20 MHz; move devices to 5 GHz.
Are devices connected without an extender in between?
If not, the likely cause
The extender is sharing airtime and halving speed.
What to do: Replace it with a wired access point or a cabled mesh unit.
Every check passed
Too many users on one access point.
What to do: Add access points where people gather and limit per-device bandwidth on guest networks.
Do all access points share the same network name and password?
If not, the likely cause
Devices must disconnect and rejoin between different names.
What to do: Use the same SSID and password on every access point.
Is transmit power set to medium rather than maximum?
If not, the likely cause
Devices cling to a far access point.
What to do: Lower power and plan channels in the controller.
Every check passed
Mixed brands or consumer routers used as access points do not roam well.
What to do: Use managed access points from one controller.
Is there an access point outside or at a window facing the area?
If not, the likely cause
Indoor access points cannot reach through outer walls.
What to do: Fit an outdoor-rated access point (IP66 or IP67) with sealed connectors.
Is the outdoor cable protected against surges?
If not, the likely cause
Lightning surges can destroy the access point and the switch port.
What to do: Add earthed Ethernet surge protection, installed by a professional.
Every check passed
Trees, walls or distance may still block coverage.
What to do: Ask for an outdoor survey before adding more equipment.
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 Thick walls or distance between the router and the room.
Solution Add an access point near those rooms, wired back to a switch.
Likely cause Congested channel, too many users on one radio, or an extender in the path.
Solution Change channel, move devices to 5 GHz, and replace the extender with a wired access point.
Likely cause Transmit power set too high.
Solution Lower power to medium and plan channels in the controller.
Likely cause More users and busy neighbouring networks.
Solution Use 5 GHz, add access points where people gather, and check the internet speed itself.
Likely cause Weak wireless backhaul through walls.
Solution Cable the unit to the network, or move it closer.
Likely cause Router and switch have no UPS.
Solution Put the router and PoE switch on a UPS with surge protection.
In Depth
Wi-Fi dead zones happen when walls, distance or a badly placed router stop the signal reaching a room. Map them with a phone, rule out cheap fixes, then add access points closer to the users, wired back to the network wherever you can.
Full bars at reception, nothing in room 12. Video calls that freeze in the kitchen. Guests complaining in reviews. Dead zones are one of the most common building complaints, and one of the most often "fixed" the wrong way, with another cheap extender plugged into a socket. If your Wi-Fi reaches everywhere but is simply slow, start with why your Wi-Fi is slow instead.
| Symptom | Likely cause |
|---|---|
| One bar or no signal in some rooms | Walls, floors or distance between the router and the room |
| Full bars but pages crawl or calls break up | Congested channels, too many users on one radio, or an extender in the path |
| Fast near the router, slow two rooms away | One router trying to cover too much |
| Phones cling to a distant access point | Transmit power set too high, so devices do not roam |
| Worse in the evening | More users, and neighbours' networks busier on the same channel |
| An extender made coverage wider but everything slower | The extender shares one radio for both hops |
Walls and floors. Thick coral-stone walls, reinforced concrete slabs, metal doors, mirrors, water tanks and lift shafts absorb or reflect Wi-Fi. A single thick stone wall can block most of the signal. Higher frequencies lose more: 5 GHz loses more through walls than 2.4 GHz, and 6 GHz loses more again.
One router trying to cover too much. A router in a corner office cannot cover a multi-storey building, however powerful it claims to be. Even if it shouts louder, a phone transmits at low power and cannot shout back through the same walls.
A bad position. Inside a metal cabinet, on the floor, behind a television or at one end of the building.
Channel congestion. Neighbouring networks on the same channel, especially on 2.4 GHz, which has only three channels that do not overlap.
Range extenders. Repeaters cover more area but cut the speed, as explained below.
Poor roaming. Access points set to full power make devices hold on to a far one instead of moving to the nearest.
Too many network names. Every SSID sends its own beacons and uses a little airtime on every channel. Two or three names are plenty.
You only need a phone and a floor plan (a hand-drawn sketch is fine).
On Android, a free Wi-Fi analyser app shows signal strength in dBm and the channels nearby networks use. On iPhone, Apple's AirPort Utility includes a Wi-Fi scanner that you switch on in the iPhone's Settings app under AirPort Utility. Stand where people actually use the Wi-Fi (the bed, the desk, the restaurant table), note your network's signal and run a speed test. Signal tells you whether the device can hear the access point; the speed test tells you whether the connection is any good.
As a rough guide:
| Signal (dBm) | What it means |
|---|---|
| −30 to −60 | Excellent to very good |
| −60 to −67 | Good: fine for video calls and streaming |
| −67 to −75 | Usable for browsing; calls may struggle |
| Weaker than −75 | Poor: expect drop-outs |
This table is a rule of thumb, and phones report signal slightly differently. Cisco's design guides use about −67 dBm at the edge of each access point's coverage as the usual target for reliable calls, assuming low background noise.
Mark the readings and the channels on your plan, along with anything solid between the router and the weak rooms. It is a basic survey, not a professional one, but it is usually enough to choose a fix.
Move or raise the router. Put it high, central and in the open: on a wall or shelf, not on the floor, not in a cabinet, away from metal and mirrors. Point external antennas vertically. It is free and sometimes enough for a small house or office.
Fix channels. On 2.4 GHz, use channel 1, 6 or 11 (the three that do not overlap) at 20 MHz width, choosing the least crowded from your scan. Wider channels on 2.4 GHz cause more interference than they are worth. Put as many devices as possible on 5 GHz, which has far more channels. Equipment certified for Wi-Fi 6E or Wi-Fi 7 can also use 6 GHz where the regulator allows it, but its range through walls is shorter still. In Tanzania the picture is not yet clear: TCRA's 2024 short range device specification lists 5945 to 6425 MHz for low-power 6 GHz Wi-Fi, but its July 2025 Wi-Fi band plan lists only 2.4 GHz and 5 GHz as licence-exempt bands. Check with TCRA or your installer before you rely on 6 GHz.
Cut the number of SSIDs to the ones you really need, usually staff and guest.
A typical plug-in extender has to receive data from the router and retransmit it to your device, often on the same radio and channel. It cannot do both at once, so the airtime is shared and throughput through the extender is roughly half what it receives at best. Chain two and it falls again. The extender also needs strong signal itself; behind a thick wall it simply repeats a weak signal. Extenders can rescue one small room. They are not a fix for a building.
A mesh system is several units working as one network with one name, helping devices move between them. Tri-band kits have a dedicated radio for the link between units (the backhaul), which avoids most of the extender loss. Mesh suits homes, villas and small offices where cabling is hard, but it meets the same walls: if units cannot hear each other through coral stone, everything after that link is slow. Most kits can use an Ethernet cable as backhaul, which is far better. Our comparison of mesh Wi-Fi and managed access points goes into detail.
For hotels, guesthouses, schools, clinics and offices, the reliable answer is ceiling- or wall-mounted access points connected by Ethernet cable, powered over that cable by a PoE switch and managed from one controller. Each access point serves a small area at moderate power, and devices roam between them. Speed does not halve, because each one has its own wired path back. A network switch with PoE ports is the heart of this design.
Good practice:
For a whole-building plan, see business Wi-Fi network design. Separate buildings are better joined by fibre than by long copper runs; see fibre optic vs Ethernet.
Plays from YouTube when you press play.
Stone Town is a UNESCO World Heritage Site, and visible changes to building exteriors need approval from the conservation authority. Plan cable routes and outdoor equipment discreetly, inside the building where possible, and check with the authority before fixing anything to a façade. Existing ducts, ceiling voids and skirting runs can often hide new cabling.
Warning Installing ceiling access points and running cable means working at height and often near electrical wiring in ceiling voids. Use a stable ladder with someone holding it, isolate nearby circuits or leave the work to qualified installers, and never drill without checking for hidden pipes and cables.
Pool decks, gardens and car parks need outdoor-rated access points (look for an IP66 or IP67 rating) with sealed connectors and stainless fixings, especially near the sea. Outdoor cable runs need surge protection and proper earthing because of lightning.
Call us if your building has several floors, many rooms or outdoor areas, or if extenders and mesh units have not solved the problem. Extrion Tech surveys buildings, designs Wi-Fi coverage and installs wired access point networks with PoE, UPS backup and central management. See our network architecture and infrastructure service or contact us with your floor plan and readings.
This guide is general information. Procedures, product features and firmware change, so check your own equipment's documentation before you start.
FAQs
Rarely. The router may shout louder, but phones and laptops transmit at low power and cannot reply through thick walls. More access points closer to users work far better than one powerful router.
Most extenders use the same radio to talk to the router and to your device, so they share airtime and roughly halve the speed. They also repeat whatever signal they receive, so behind a thick wall they repeat a weak one.
Mesh with every unit cabled comes close. Wireless mesh is good for homes and small offices, but in large buildings with thick walls, wired access points are faster and more reliable.
Both. 2.4 GHz travels further through walls but is crowded and slower; 5 GHz is faster with more channels but shorter range. Placing access points close to users makes 5 GHz usable throughout.
It depends on wall materials, layout and the number of users. In coral-stone or concrete buildings, plan on more than you would expect, often one per room or two. A survey is the only reliable way to tell.
You can do a basic one with a phone app as described above, and it is useful. A professional survey uses calibrated tools and predictive planning, and is worth it for hotels, hospitals and large offices.
Usually one Ethernet cable to each access point, carrying both data and PoE power. Existing cables can sometimes be reused if they test well and reach suitable spots.
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.
Keep learning
Networking, Wi-Fi & Fibre Optics
20 min
Troubleshooting fix
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 hal...
View Guide
Networking, Wi-Fi & Fibre Optics
30 min
Troubleshooting fix
When a MikroTik router loses the internet, the fault is almost always in one of five places: the line from the ISP, the WAN address, the default route...
View Guide
Networking, Wi-Fi & Fibre Optics
40 min
A reset wipes a MikroTik router back to its default configuration, or to nothing at all. Done well it takes twenty minutes; done in a hurry it erases...
View Guide
Networking, Wi-Fi & Fibre Optics
25 min
When staff say "the internet is slow", the connection is often not the problem: it is one router trying to serve forty devices through stone walls. Th...
View GuideEngineers reply Mon – Fri, 08:00 – 17:00
We'll send a copy of the conversation to our team. Next time, the chat starts fresh.
