Why your WiFi dies in the back bedroom

Your router works fine in the living room. Two rooms away, video calls stutter. Nothing is broken — the signal is being eaten by the building.

Radio waves lose energy every time they pass through something

A WiFi signal is radio, and radio gets weaker with distance and with every material it crosses. Two identical houses can perform completely differently depending on what the walls are made of.

Roughly, from least to most damaging:

• Drywall and wood. Barely noticeable. A modern interior wall costs you very little.
• Glass and hollow doors. Minor.
• Brick, concrete, and tile. Significant. A brick chimney in the middle of the house is a wall your signal has to go around.
• Lath-and-plaster with wire mesh. Severe. The wire behaves like a screen that reflects radio energy.
• Stucco over wire lath. Severe, and it wraps the whole building. This is why so many Bay Area homes have terrible patio coverage.
• Foil-backed insulation and radiant barrier. Severe. Common in retrofitted attics, and it blocks signal from travelling upward between floors.
• Mirrors and metal-framed glass. A large mirrored closet door is a reflector sitting in the middle of your hallway.
• Water. Aquariums, water heaters, and full pipes all absorb 2.4 GHz energy well.

Older Peninsula and San Francisco housing stock tends to combine several of these at once: plaster interior, stucco exterior, retrofit insulation. That combination will defeat any single router regardless of price.

Faster bands travel shorter distances

This trips people up constantly. Modern WiFi uses several frequency bands, and they behave differently:

• 2.4 GHz travels furthest and penetrates walls best, but it is slow and heavily congested.
• 5 GHz is much faster and loses far more energy through walls.
• 6 GHz (WiFi 6E and WiFi 7) is faster still and barely leaves the room it started in.

So a house can look perfectly healthy if you only measure 2.4 GHz, and be unusable for video calls on 5 GHz in the same spot. When somebody says "I have full bars but it's slow," this is usually why — the phone is clinging to a distant, congested 2.4 GHz signal.

Your phone decides when to switch, and it decides badly

Devices are reluctant to let go of a connection. Walk from the kitchen to the back bedroom and your laptop will often hang onto the far-away router at a terrible signal level rather than switch to a closer access point. This is called sticky client behaviour, and it is why adding a second router with a different network name rarely helps — you end up manually switching networks, or not switching at all.

Properly configured access points sharing one network name can nudge devices to move at the right moment. That is a configuration decision, not something that happens automatically by buying more hardware.

What actually fixes it

Move the router first. It is free. A router in a corner closet is broadcasting half its energy into the neighbour's yard. Central and high beats hidden and low, every time.

Add access points where the signal has to arrive, not where the outlet is. One well-placed unit at the far end of the house does more than an expensive router at the front.

Run a cable if you can. An access point fed by Ethernet has its full radio capacity available for your devices. One fed wirelessly spends a share of that capacity talking back to the router, and the further away it is, the worse the trade.

Aim for a real number. Signal strength is measured in dBm, always negative, closer to zero being stronger. Design for −67 dBm or better everywhere you care about. That is the accepted threshold for dependable voice and video. Below −70 you will notice problems; below −80 it is effectively dead.

Measure before you buy anything

Free apps such as WiFiman will show you live signal strength in dBm as you walk around. Spend ten minutes writing down the reading in each room, including the yard and garage. That single sheet of paper tells you whether you have a coverage problem, a congestion problem, or a router placement problem — and stops you buying hardware that was never going to help.