Apartments break WiFi in ways houses simply do not. The room is small, but every neighbour's network is sitting on top of yours. The walls are concrete instead of stud. The router was put in a cupboard during build because it kept the show flat tidy. The ONT was fixed wherever the developer's electrician fancied. There are thirty visible SSIDs from your sofa. None of this is the router's fault — it is doing its best in a hostile environment. After years of fixing WiFi London apartment jobs across mansion blocks, ex-council stock, period conversions and shiny new-build towers, I can tell you the diagnosis is usually the same handful of issues, and the cure rarely involves the kit the homeowner expected to buy.
Why London flats have such bad WiFi
London is one of the most spectrum-congested cities in Europe. From a Bermondsey balcony I can routinely see thirty or more 2.4 GHz networks and almost as many 5 GHz ones — neighbours, communal landlord-fitted WiFi, the corridor-mounted access points the managing agent installed for "smart concierge", every door-bell camera, every smart-meter, every Bluetooth-bridging hub. All of it lives in the same handful of radio channels. Your router is shouting in a stadium.
Then layer on the buildings themselves. Edwardian mansion-block conversions have thick lath-and-plaster internal walls that swallow 5 GHz with embarrassing ease. Ex-council blocks have reinforced concrete walls with rebar that effectively act like Faraday cages between rooms. New-build apartments have plasterboard partitions that look thin but are layered with acoustic insulation, sometimes foil-backed, and double-skinned for fire compartmentation — which kills WiFi as a side-effect. None of these buildings were designed with radio propagation in mind. They were designed for living in.
Finally, the router itself. In nine out of ten flats I visit, the router is either in a cupboard, behind a sofa, on the floor under a desk, or in a hallway niche the developer specified during fit-out. None of those positions are good. The router needs to be high, central and in free air. The cupboard is the enemy.
The router-in-the-cupboard problem
This deserves its own section because it is the single most common cause of bad WiFi in a London flat. In new-builds, the developer sites the ONT and the master socket in a service cupboard — usually behind a kitchen unit, in a hall closet, or in a meter cupboard on the front door. That cupboard is then closed by whatever the resident puts in front of it: coats, shoes, a Hoover, dog leads, a Brita filter, six pairs of trainers. The router lives inside, broadcasting through the back of a wardrobe.
The fix is not "buy a stronger router". The fix is to move the antenna out of the cupboard. There are two real ways to do that:
- Move the entire router. Run the WAN cable from the ONT (or the NTE5A/NTE5C master socket for copper) to a better location — usually a hallway shelf or a living-room wall — and let the router live there. Cable is cheap and well hidden along skirtings.
- Leave the router in the cupboard and add a wired access point. A single AP, fed by a short Cat6 run from the cupboard out into the main living space, broadcasts cleanly into the rooms that actually matter. This is the route I take when the cupboard houses the ONT, the smart-meter hub, the alarm panel and is genuinely fine for utility services — just not fine as a radio location.
Either way, the principle is the same: the radio needs line-of-sight to the rooms it serves. A cupboard door, the back of a wardrobe and a coat rail are not line-of-sight. The why boosters fail piece explains why simply plugging an extender into the corridor does not fix this.
Channel saturation and what a heat map actually shows
The other thing I almost always have to explain on apartment jobs is signal-to-noise ratio (SNR). It is not enough to have a strong signal from your own router — your router has to be heard above the noise floor of everyone else's. In a busy central-London block, SNR matters more than raw signal strength. A router showing two bars on your phone with a quiet noise floor will outperform a router showing four bars with another twelve networks fighting over the same channel.
That is what a proper WiFi survey actually measures. I walk every room with a calibrated analyser, capture the signal level of your network and every other network in earshot, and overlay them on a floor plan. The result tells me three things at once:
- Where your coverage genuinely fails.
- Where it looks fine but is contested — i.e. where neighbours are stamping on your channel and you would not know without the survey.
- Which 5 GHz channels are clean enough in your specific flat to use without interference.
The point I make to apartment owners: 2.4 GHz in central London is, for practical purposes, a write-off. Use it only for low-bandwidth IoT — smart bulbs, a doorbell, a thermostat. Keep your laptops, phones and TVs on 5 GHz where the channels are wider, the noise is lower and the throughput is real. WiFi 6 (802.11ax) helps because it handles dense environments much better than older standards, but it is not magic — it still needs a clean channel to live on.
FTTP, ONT placement and why it matters in a flat
Full-fibre changes the apartment WiFi conversation. Once your block is connected to FTTP, the ONT (Optical Network Terminal) is the new master socket — it is where the fibre lands and the Ethernet starts. The trouble is the ONT is fixed by the installer wherever they can drill, which is often the worst possible spot for the router that connects to it.
I have lost count of new-build studios where the ONT is in a hall cupboard the resident never opens, with the router velcroed to the side of it. The fibre cannot be extended easily — it is glass — but the Ethernet from the ONT to the router can run as far as you like up to a hundred metres. So the answer is to wire from the ONT to wherever the router actually wants to live, not to leave the router glued to the ONT. On any flat with FTTP I do, that single move is the first thing I plan. The broadband engineer page covers the FTTC-to-FTTP transition and what the ONT actually does.
Single-AP placement strategy for flats
Unlike a house, an apartment usually does not need multiple access points. One good AP, well placed, will cover almost any London flat under about a hundred and twenty square metres. The trick is the placement, not the count.
What "well placed" means in practice:
- Central. Equidistant from the rooms that matter. A hallway ceiling near the centre of the flat almost always wins.
- High. Ceiling-mounted beats shelf-mounted. The radiation pattern of a domestic AP is broadly hemispherical pointing down — put it where the down-cone covers the living space.
- Free of obstruction. Not behind a TV, not on top of a fridge, not in a metal-cased media unit, not next to the microwave.
- Wired. A PoE-fed access point on a single Cat6 run is the cleanest install in a flat — no plug, no transformer, just one cable disappearing into the ceiling void.
If a flat truly needs two APs — usually because it is long and thin, or because one end is behind a particularly bad wall — they need to be wired to each other rather than meshed wirelessly. The mesh vs wired article goes into why this matters; the short version is that wireless backhaul inside a flat surrounded by other networks performs poorly compared with a single Cat6 down the skirting.
Scenario one — Edwardian mansion-block conversion in Maida Vale
Mansion blocks are some of my favourite buildings to work in and some of the most challenging for WiFi. The flat in question was a two-bedroom conversion on the third floor of a 1905 red-brick block — original lath-and-plaster walls, deep moulded cornices, sash windows, and roughly forty other flats in the same building all running their own networks.
The owner had bought three different mesh kits over two years. None had worked properly. The kitchen at the back of the flat ran at dial-up speeds. The bedroom was occasionally usable. The router lived in a hallway cupboard near the front door because that is where the BT master socket was, and that is where the ISP installer left it.
What actually fixed it:
- I confirmed by survey that 2.4 GHz in the flat was essentially unusable because of the neighbouring networks — twenty-three SSIDs visible on that band from the kitchen alone.
- I ran a single Cat6 cable from the hallway cupboard, along the picture-rail line behind the cornice (where it is invisible from below), into the ceiling void above the living-room/kitchen open-plan area.
- I fitted a PoE WiFi 6 access point flush to the ceiling, central to the flat.
- I disabled the router's own WiFi entirely and put it in pure modem-and-routing mode, so there was only one radio broadcasting in the flat — and so the channel could be chosen carefully.
- I picked a 5 GHz channel that was quiet in this specific flat (the cleanest channel from a survey on the ground floor of the same block was the noisiest on the third floor — every flat is different).
Speeds in the back kitchen went from struggling to do video calls to running on the full FTTP line. The job took half a day. The owner had already spent more on mesh kits over two years than the install cost.
Scenario two — ex-council flat in Bermondsey, concrete walls, thirty neighbours
Ex-local-authority blocks are a particular case. The construction is reinforced concrete throughout — floors, walls, ceilings — and the steel reinforcement effectively shields each room from the next. WiFi from the hallway barely reaches the master bedroom even when the hallway is only three metres away, because the concrete spine wall between them might as well be a sheet of metal at WiFi frequencies. The piece on building materials and WiFi loss covers the physics.
The flat in question was a two-bedder on the ninth floor of a 1970s block. The owner had spent six months in a battle with their ISP. They had been sent three replacement routers, one outdoor "long-range" antenna and a TV-aerial-shaped extender. None of it had made any difference.
What I did:
- Surveyed the flat and confirmed thirty-one visible WiFi networks from the living room — including several from the corridor outside.
- Identified the concrete spine wall between the hallway and the bedrooms as the cause of the dead zone.
- Pulled a single Cat6 from the hallway cupboard, drilled (with the freeholder's permission) through one carefully selected internal stud return rather than the concrete itself, and dropped the cable into the master bedroom's ceiling void.
- Fitted a single AP in the bedroom hallway ceiling, central to the two bedrooms and bathroom.
- Left the existing router covering the living/kitchen end of the flat, but switched it to a clean 5 GHz channel I had verified was quiet in this specific block.
The cost of the fix was a fraction of what the resident had already spent on hardware that did not work. The lesson — and I say it on every apartment job — is that the kit you buy from a high-street shop has no way of knowing your neighbours exist.
Scenario three — Nine Elms new-build studio
New-builds present a different problem. The walls are thinner and the floors are quieter, but the developer's idea of "structured cabling" is usually one Ethernet socket in the living room (often un-terminated at the other end) and an ONT in a hall cupboard.
The flat in question was a forty-five-square-metre studio on the eighteenth floor of a Nine Elms tower. FTTP installed at build, ONT in the entrance cupboard, router velcroed next to it. The cupboard door closed against the back of a sofa. WiFi crashed every video call.
What I did:
- Confirmed by survey that with the door open the signal was acceptable; with the door closed, it dropped by twenty decibels — the cupboard itself was the problem.
- Ran a Cat6 from the ONT in the cupboard along the skirting, behind the sofa, up into the corner of the living/sleeping area, and into a wall-mounted access point at high level.
- Left the router in the cupboard, with its own WiFi switched off. The ONT and router could stay where the developer wanted them. The radio simply moved out into the room.
The total disruption was a few cable clips along the skirting and one neat AP. The before-and-after on the speed test was night and day.
Quick wins you can try before calling an engineer
Most apartment WiFi can be improved noticeably before any cable goes in. None of these are a substitute for a proper survey, but they are worth trying:
- Move the router into open air. Out of the cupboard, off the floor, away from the TV.
- Restart the router once. Restart your phone. Forget the network and rejoin. (Genuinely — modern routers do choose better channels after a power-cycle.)
- Use the 5 GHz SSID for your devices and reserve 2.4 GHz for smart-home gear.
- Update the router firmware. Most ISP routers will not have done this on their own.
- If your block has a residents' corridor AP, opt out of it. It is usually shouting on the same channel as your flat's router and making things worse.
If you have done all of that and the problem is still there, you have a structural issue — building fabric, ONT placement, or contention — and that is when a survey earns its keep. The heat-map survey article covers what the visit involves.
What I actually install in a London flat
To set expectations — when I leave a typical apartment job, the kit list is small:
- One properly placed, ceiling-mounted PoE access point (occasionally two for awkward layouts).
- A short Cat6 cable run, almost always hidden in skirting, picture-rail line or ceiling void.
- A small PoE injector or compact switch in the same cupboard as the ONT/master socket.
- The existing ISP router, reconfigured to stop its own WiFi from fighting the new AP.
- A clean SSID set with proper band steering, picked channels, and WiFi 6 turned on for clients that support it.
That is it. There is no rack, no patch panel, no enterprise console. Apartments do not need the cabinet-and-switch setup that big houses do. They need the radio out of the cupboard and on to the ceiling.
The honest summary
If your London flat has bad WiFi, you almost certainly do not have a "WiFi" problem in the way the high-street shops want to sell you. You have a placement problem, a channel-saturation problem, or a building-fabric problem. Mesh kits and extenders rarely fix any of those. A single well-placed access point, wired to the existing router, almost always does. Pair that with a proper channel choice based on your specific flat, your specific neighbours and your specific concrete wall, and the result is the WiFi you thought you were paying for in the first place.
Ring 020 3633 1131. Honest advice, freely given.
