L'équipe Texto SMS Gratuit
27 August 2026 · 12 min read
Introduction: fibre stops at the router
There is one sentence that provider support agents repeat hundreds of times a day, and which is technically accurate even if it goes down badly: your fibre subscription stops at the router. What happens after that — in the air of your flat, through the load-bearing walls, between the router and your son's phone — no longer belongs to the operator's network but to a domestic radio link that you alone control.
This is the industry's number one misunderstanding. A household signs up to a plan advertised at 1 Gbps, measures 45 Mbps on a laptop in the back bedroom, and logically concludes that "the fibre isn't working." In the vast majority of cases, the fibre works perfectly: it is the last few metres, the ones crossing two partitions and a structural wall, that collapse the throughput.
In 2026, the topic has become more sensitive than before, for three reasons. First, the gradual switch-off of ADSL is pushing millions of households onto fibre, with very high performance expectations. Second, the number of connected devices per home has exploded: television, speakers, vacuum cleaner, thermostat, cameras, consoles — each one consumes airtime even when it appears to be doing "nothing." Finally, radio density in apartment blocks has reached unprecedented levels: in a Parisian tower block, a Wi-Fi scan routinely reveals forty to sixty neighbouring networks all competing for the same channels.
This guide offers an ordered method: measure before spending, understand what physics allows, then choose the right hardware. In that order.
Step 1: establish the truth about your speed, not the impression
Before buying anything, you need two measurements, not one.
Measurement A — over Ethernet. Plug a computer directly into a LAN port on the router with a network cable, switch off the machine's Wi-Fi, and run a test using a serious tool. The Arcep measurement site (via the "Mon réseau mobile" API on the mobile side, and the certified tools on the fixed side), nPerf or Speedtest will all do the job. This value is your real line speed.
Measurement B — over Wi-Fi, in the same room as the router, then in the problem room.
The gap between A and B tells the whole story:
| Finding | Interpretation | Where to act |
|---|---|---|
| A low (far from the subscribed plan) | Line, optical socket or connection problem | Provider / Arcep |
| A good, B good near the router, B collapsed further away | Radio propagation, obstacles, range | Placement + hardware |
| A good, B poor even at 2 metres | Saturated 2.4 GHz band, congested channel, firmware | Router settings |
| Decent throughput but erratic latency | Interference, channel saturation, neighbouring networks | Band/channel choice |
This distinction follows the same logic applied to mobile networks: you don't fix a coverage problem with a handset setting, and vice versa. A simple Cat 6 Ethernet cable a few metres long, kept in a drawer, remains the most cost-effective diagnostic tool a household can own — and incidentally the best permanent solution for a desktop computer or a console.
Note too that the measurement depends heavily on the device. A 2019 laptop with a Wi-Fi 5 card will cap well below what a Wi-Fi 6E router can deliver. Sometimes the weak link is in your hand.
Step 2: understand why the walls always win
Wi-Fi obeys a simple physical constraint: the higher the frequency, the higher the potential throughput, and the shorter the range through obstacles.
- 2.4 GHz: passes through walls well, comfortable range, but a narrow, heavily congested band (it shares space with Bluetooth, microwave ovens and certain connected devices) with modest speeds.
- 5 GHz: the current sweet spot, high speeds, more channels, but clear attenuation from the second wall onwards.
- 6 GHz (Wi-Fi 6E and Wi-Fi 7): new spectrum, so virtually free of neighbouring traffic, with very low latency — but reduced range and maximum sensitivity to obstacles. In France, indoor use of the 6 GHz band is regulated, with power limits that further accentuate this "single room" behaviour.
In practical terms: a plasterboard wall costs few decibels, a hollow brick partition costs more, and a reinforced concrete load-bearing wall or a floor between storeys can cause a spectacular drop in signal. The wall mirror, the reinforced door, the large television screen and the fridge are genuine obstacles, not forum myths.
Two placement mistakes dominate in French homes:
- The router inside the TV unit, wedged behind a wooden panel, between the soundbar and the set-top box. The signal starts out handicapped.
- The router in the hallway, because that's where the optical socket is — in other words in a corner of the home, with half the radiation heading off to the neighbours or into the stairwell.
The theoretical ideal remains a central point, high up, unobstructed and out in the open. Rarely compatible with the reality of a flat, which brings us to the next step.
Step 3: the free settings to try before buying anything
Before reaching for your bank card, four settings accessible from your router's admin interface (Freebox OS, the Livebox area, the SFR or Bbox interface) often change everything.
Splitting the bands, or not
By default, most routers broadcast a single network name (SSID) for both 2.4 and 5 GHz, letting the device choose. This mechanism, band steering, works fine… when it works. It also produces absurd situations: a television three metres from the router that stays stuck on 2.4 GHz because it connected there once.
Temporarily creating two separate SSIDs (for example MyRouter and MyRouter_5G) lets you force speed-sensitive devices — work-from-home computer, 4K TV, console — onto 5 GHz, and leave low-bandwidth connected objects on 2.4 GHz. Less elegant, often more effective.
Choosing the right channel
On 2.4 GHz, only three channels don't overlap: 1, 6 and 11. If your forty neighbours are all on 6, switch to 1 or 11. A Wi-Fi analyser app on an Android smartphone, or a utility on a computer, will map the neighbourhood in thirty seconds. On 5 GHz, channel width matters just as much: 80 MHz gives throughput, 40 MHz gives stability in a busy environment.
Update, then restart properly
Router firmware evolves, fixes genuine radio bugs, and sometimes resets settings. A full power cycle (unplugged for 30 seconds) clears the channel table and resolves a surprising number of gradual slowdowns.
Check what's using the bandwidth
A cloud backup running in the background, a console downloading a 90 GB update, a computer syncing a drive: Wi-Fi is a shared medium, and everyone waits their turn. The router interface lists connected devices and their traffic. Look before blaming the provider.
Step 4: extender, powerline or mesh — the real comparison
Once the settings are exhausted, you need to extend coverage. Three families of solution coexist, and they are not equivalent.
The simple Wi-Fi extender
It picks up the router's signal and rebroadcasts it. Simple, cheap, immediately available. Its flaw is structural: on a single-radio extender, the device listens and re-transmits on the same radio, which halves the usable throughput at best. Worse, if it is placed where the signal is already weak, it faithfully rebroadcasts… a bad signal.
Golden rule: an extender goes halfway, in a zone where the router's signal is still clearly good, never in the dead room. A dual-band Wi-Fi 6 extender with an Ethernet port remains a defensible purchase for covering a bedroom or a terrace without building work.
Powerline adapters (PLC)
They send data over the electrical wiring. Excellent in a multi-storey house where radio doesn't reach, disastrous when the sockets are on different phases, behind a surge protector, or in an old installation. The performance figures on the box (1000, 2000 Mbps) are purely theoretical; in practice, expect a fraction of that number. A powerline kit with a Wi-Fi access point works remarkably well for a garage, a cellar or a converted attic — provided you test it in your own home and can return it if the result disappoints.
The mesh system
Several units cooperate, forming a single network with a single name, handling the handover from one point to another as you move around, and — on tri-band models — reserving an entire band for the backhaul link between units. It is the most accomplished solution for a home larger than 90 m², a sprawling single-storey house or a duplex. A tri-band mesh Wi-Fi system represents a bigger investment, but avoids piling up sticking plasters.
| Criterion | Extender | Powerline | Mesh |
|---|---|---|---|
| Budget | Low | Medium | High |
| Throughput loss | High | Variable | Low |
| Seamless roaming | No | No | Yes |
| Depends on the building | Radio | Electrics | Radio |
| Ideal use case | One room to cover | A floor or outbuilding | Large home |
The best compromise, often forgotten: wired mesh. If you can run a discreet Ethernet cable along a skirting board to the second unit, you get mesh coverage with no radio loss at all. This is the setup most professionals choose for themselves.
Step 5: the special cases that trip people up
The new-build home that's too well insulated
Recent thermal regulations have made metallised vapour-barrier insulation and low-emissivity glazing standard. These materials are excellent wave reflectors. The paradoxical result: an energy-efficient new home can be a radio nightmare, with a signal that crosses neither walls nor windows — hence the value of fibre up to the router and cable beyond it.
The saturated apartment block
In a dense building, the problem is not power but congestion. Increasing transmit power achieves nothing if everyone is talking at once: it is the number of simultaneous conversations that blocks things, not the volume. The 6 GHz band, still sparsely populated, is the real answer here — provided you have Wi-Fi 6E or Wi-Fi 7 devices.
Remote working and video calls
Video calls don't need much bandwidth (a few megabits) but they do demand stable latency and low jitter. A Wi-Fi link showing 300 Mbps at its peak but dropping out in fits and starts will ruin a meeting, whereas a wired 100 Mbps connection will be flawless. For a stationary workstation, a USB Ethernet adapter costing a few euros settles the question once and for all on a laptop without an RJ45 port.
Temperamental connected devices
Many smart home products only work on 2.4 GHz and refuse to pair if the smartphone is connected on 5 GHz. If installing a bulb or a camera fails systematically, temporarily switch your phone to the 2.4 GHz network.
What you can demand from your provider
Not everything is down to you. There are cases where the provider must step in:
- Wired throughput far below the plan: this is a connection, optical socket or network configuration problem. The provider must investigate.
- Repeated drops of the link (the router loses the fibre, not the Wi-Fi): an incident on the network or at the mutualisation point. Disconnections linked to work in street cabinets remain a frequent source of complaints, extensively documented by Arcep in its work on FttH connection quality.
- Obsolete equipment: an older-generation router, still on Wi-Fi 5, can often be replaced on request, sometimes free of charge, sometimes for a monthly supplement. It's worth asking.
If the problem persists after reporting it to customer service, the "J'alerte l'Arcep" platform lets you report a malfunction on a fixed, mobile or postal network. It does not handle individual disputes, but it feeds the regulator's monitoring — and mass reporting has historically triggered corrective action.
Think about physical protection too: a router and a mesh system are permanently powered electronic devices, sensitive to power surges. A correctly rated surge-protected power strip is discreet insurance for a modest cost. Be careful, though: plugging a powerline adapter into a surge protector generally wipes out its performance — the two devices do not get along.
The method in summary
- Measure over Ethernet to find out your line's real capacity.
- Measure over Wi-Fi near the router, then in the problem area.
- Move the router: high up, unobstructed, in the most central position possible.
- Adjust the settings: split the bands, pick a free 2.4 GHz channel, choose an appropriate channel width, keep the firmware up to date.
- Extend only after that, choosing according to the building: an extender for one room, powerline for a difficult floor, mesh for a large home — and Ethernet cable whenever it is physically possible.
Conclusion: the last few metres are your responsibility
The rollout of fibre in France solved a historic capacity problem. It created another, subtler one: the growing gap between what arrives at the front door and what actually reaches the devices. A 1 Gbps subscription guarantees nothing beyond the router, and no provider can push a 6 GHz wave through a load-bearing wall.
The good news is that these last few metres are the only segment of the chain you control entirely. An afternoon of measurements, a couple of settings, perhaps a cable along a skirting board, and the speed you pay for becomes the speed you get. That is often cheaper — and always quicker — than switching provider on the basis of a bad diagnosis.
