Router in a cabinet? That is why the bedroom is dead

Your router sits neatly inside a closed cabinet under the TV. The living room gets full bars. The bedroom gets one, sometimes none. Nothing is broken: the router is doing its job inside a box that was designed to hide things, and radio does not like being hidden.

This is the cheapest fault in the house to find and to fix, and you can prove it in ten minutes without buying anything.

Test the signal, not the bars

Bars lie. They are rounded, every phone draws them differently, and one bar can mean anything. Signal strength is measured in dBm: a negative number where closer to zero is better.

Install any free WiFi analyser app. Every one of them shows dBm.
Stand one metre from the router, in the open, and write the number down.
Open the cabinet door, or lift the router out, and read it again in the same spot.
Walk to the room where it hurts, hold the phone at normal height, and read it there.

What you see	What it means
-45 to -55 dBm next to the router, -65 to -70 in the far room	Normal. That room is simply far away.
-60 to -70 inside the cabinet, -75 or worse in the room	The cabinet is eating your coverage.
The number jumps 8 dB or more when the door opens	The enclosure is the problem. Move the router out today.
-45 in the open, still -80 in the room	Distance and walls, not the cabinet. This is where extra hardware starts to make sense.

3 dB is roughly half the power, and 10 dB is roughly a tenth. So an 8 dB jump from opening one door is not rounding error, it is a real slice of your coverage gone.

What actually eats the signal

In the way	Rough cost at 5 GHz	Why
Metal cabinet, DB box, fridge, metal shelving	20 dB or more	Metal reflects and blocks radio instead of passing it through
Mirror, or glass with metallic film	10 to 20 dB	The reflective coating is a thin layer of metal
Concrete wall, 100 to 150 mm	12 to 20 dB	Dense, and often full of steel mesh
Timber cabinet doors, a closed bookcase	2 to 6 dB	Wood is mild, but a closed door still costs you
Water: aquarium, water tank, bathroom wall with pipes	Varies, often 10 dB or more	Water absorbs 2.4 GHz and 5 GHz alike
A stack of boxes, clothes or books around the router	2 to 10 dB	It is the same problem as a cabinet, just untidier

Notice what is missing from that table: plastic. A plastic cover or a plastic door is nearly transparent to WiFi. If you must hide the router, hide it behind plastic and leave both ends open for air.

The three worst spots

Inside the TV cabinet, or behind the TV. The screen, the speakers and the shelf pins are all metal or metal-ish, and the router's antennas end up pointing at a wall of it. Fix: open shelf, at least half a metre away from the TV, antennas upright.
Inside the DB box or a metal shoe cabinet by the front door. A distribution box is a metal box in the corner of the house: the two worst things you can do to a radio at once. Fix: put the router on a shelf in a room people actually use, and run a LAN cable back to the box.
On the floor, beside the fridge, the aquarium or a bathroom wall. Low position, metal on one side, water on the other. Fix: 1.2 to 1.8 m up, out in the open, and a metre of clear space from anything metal or wet.

Two causes the cabinet hides

Heat. A router in a closed box has no airflow. It runs hotter, and heat makes a radio unstable before it makes it fail outright: you get random drops, slower throughput in the evening, and a device that behaves after a restart because it finally cooled down. If your router is warm to touch and boxed in, that alone is worth opening it up.

Small appliances in the same corner. The same cabinet area usually holds a microwave, a cordless phone base, a baby monitor, a wireless doorbell chime and a Bluetooth speaker. Most of those share the 2.4 GHz band and chat constantly. That is why 2.4 GHz can be worse than the shorter-range 5 GHz in a corner like this.

When the cabinet is innocent

If the dead room is two concrete walls away, or at the far end of a long terrace house, moving the router out of the cabinet will help a little and not enough. That is a coverage problem and it needs a second point, not a better box. Compare the options in mesh vs WiFi extender vs powerline before you spend, and check which band the room is failing on in 2.4 GHz vs 5 GHz vs 6 GHz.

Before you buy anything

Carry the router to the middle of the house, plug it in, and test the dead room again. Five minutes, zero ringgit. If the room comes alive, you needed a longer cable, not a mesh kit. If the room is still dead with the router standing free in the open, now you know, and you can buy the right thing once.

Quick answers

Does a wooden cabinet block WiFi signal?

Wood on its own barely does. The problem is usually everything with it: metal hinges, metal shelf pins, a metal back panel, a mirror on the door, or a stack of stuff packed around the router. If the signal jumps when you open the door, treat the whole enclosure as the fault, whatever it is made of.

Can I leave the router inside the DB box if the cover is plastic?

Better not. Distribution boxes are usually metal, they sit in a corner of the house, and they hold breakers and wiring that nobody wants to squeeze a router next to. The corner is nearly always the worst position for coverage, even before you count the metal.

Is a mesh node in the dead room enough if the router stays in the cabinet?

No. A node that receives a weak, noisy signal can only rebroadcast a weak, noisy signal. Fix the source first, then add a node only if the room is still dead after the router is out in the open.

How far can I move the router from the fibre point?

As far as a longer fibre patch cord and a LAN cable will reach, and both are cheap parts. Ask for a longer cord, keep it loosely coiled, and never bend it tighter than a coin. Moving the router a few metres to a shelf in the middle of the house beats almost any setting you can change.