How to find and fix Wi-Fi dead zones

A Wi-Fi dead zone is a part of your home where the signal is too weak, below roughly −75 to −80 dBm, for a steady connection. You find one by walking slowly through your home with a live signal reading and marking where it drops. You fix it by moving the router, removing what blocks the signal, or adding a mesh point or extender near the weak area.

What causes a Wi-Fi dead zone?

Wi-Fi signal weakens with distance and with everything it passes through. A dead zone forms where those losses add up. The usual causes are:

• Distance. A router at one end of a long house may barely reach the other end.
• Thick or dense walls. Brick, stone, concrete and plasterboard with metal studs absorb a lot of signal.
• Floors and ceilings. Each floor between you and the router costs signal, and concrete floors cost more.
• Metal and water. Radiators, fridges, mirrors, metal shelving and fish tanks all block or reflect Wi-Fi.
• Interference. On 2.4 GHz, microwaves, some baby monitors and crowded channels can drown out a weak signal.
• Router position. A router on the floor, inside a cupboard or behind a TV starts at a disadvantage.

How to find your dead zones

Guessing wastes effort. Measure instead.

1. Pick a fixed way to hold your phone, at chest height, the same way every time.
2. Start next to the router and note the signal in dBm. This is your best case.
3. Walk slowly through each room, stopping for a few seconds in the middle and in the corners.
4. Note where the signal falls below about −70 dBm. That is where streaming and video calls start to struggle.
5. Mark spots below about −80 dBm as dead zones. Connections there will drop or crawl.
6. Check upstairs, the garden and any outbuildings if you use Wi-Fi there.
7. Run a speed test in the worst spots, to see how the weak signal affects real use.

A rough sketch of your floor plan with readings written on it makes the pattern easy to see. For a fuller method, see how to measure Wi-Fi strength room by room.

How to fix a Wi-Fi dead zone, cheapest first

Work through these in order. The first few are free.

1. Move the router

Router position is the biggest single factor. Put it as central and as high as you can, in the open, away from metal and large appliances. Even a move of a metre or two, or onto a shelf, can make a difference. Where to put your router for the best Wi-Fi covers this in detail.

2. Clear the path

Look at what sits between the router and the weak room. A mirror, a fridge, a metal cabinet or a fish tank in a line between them may be enough to create a dead zone. Moving that object, or the router, can help.

3. Try the other band

In a far room, 2.4 GHz often reaches better than 5 GHz. If your router uses separate network names for each band, connect to the 2.4 GHz one in that room and compare. If it uses one name, your device should choose, but it does not always choose well.

4. Change the channel

If the signal is not terrible but the connection is still poor, congestion may be adding to the problem. A quieter channel can help a borderline area.

5. Add coverage

When distance and walls are simply too much for one router, you need a second source of signal near the dead zone. Your options are:

• A mesh Wi-Fi system, which uses several units working together under one network name
• A range extender, which repeats the router's signal from a point in between
• A wired access point, connected to the router by a network cable, which gives the best performance if you can run a cable
• Powerline adapters with Wi-Fi, which carry the connection through your home's electrical wiring, with results that vary by home

Which to choose is covered in mesh Wi-Fi vs a range extender.

Where to place a mesh unit or extender

Place it about halfway between the router and the dead zone, where the signal is still decent. A common mistake is putting it inside the dead zone itself. If the unit cannot hear the router well, it can only pass on a weak signal.

A good rule of thumb is to place it where your phone still shows around −65 dBm or better from the main router.

After any change, measure again

Repeat your walk with the same phone held the same way. Compare readings spot by spot. Real improvement shows up as several dB in the problem rooms, not just a different number of bars.

How CellRadar helps

CellRadar has a Dead-zone Walk Map: you walk a room and it colours each spot by its measured Wi-Fi signal, so a Wi-Fi dead zone shows up clearly. The Wi-Fi Meter gives a live strength gauge for finding the best place for a router or mesh unit, and the Wi-Fi Analyzer suggests a quieter channel. It measures and points to the fix; the fix itself is a change you make at home.

Frequently asked questions

What signal strength counts as a Wi-Fi dead zone?

There is no fixed line, but below about −80 dBm most devices struggle to stay connected. Between −70 and −80 dBm, connections work but are slow and unstable.

Can a dead zone move?

Yes. Moving furniture, adding appliances or changing the router position all change where signal reaches. Neighbouring networks can also affect borderline areas.

Will a more powerful router fix my dead zone?

Sometimes, but not always. Your phone also has to send signal back to the router, and its power is limited. A second access point near the weak area is usually more reliable.

Is it safe to put my router in a cupboard?

It is safe, but it weakens your Wi-Fi, especially if the cupboard has a solid or metal door. Keep it in the open if you can.