Updated
Quick fix
Put the router in a central, open, raised spot away from metal and thick walls. If coverage is still weak, use a mesh Wi-Fi system or, for offices, wired access points. Avoid cheap range extenders where you can.
Step by step
Move the router
Place it high, central and in the open, not in a cabinet, a closet or behind a TV. Every wall, floor and appliance between you and the router weakens the signal.
Keep it away from interference
Microwaves, cordless phones, baby monitors, metal shelves, mirrors and fish tanks all hurt Wi-Fi.
Use the right band
Many routers broadcast 2.4 GHz (longer range, slower) and 5 GHz (faster, shorter range), and newer ones add 6 GHz. Devices far away may do better on 2.4 GHz.
Update the router
Install firmware updates from the router’s app or settings page. Very old routers may simply be too weak for the space.
Consider mesh Wi-Fi
A mesh system uses two or more units that work as one network with one name. Place the second unit about halfway between the router and the dead zone, not in the dead zone itself.
For offices, wire it
Business access points connected back to the network with Ethernet cables give the most reliable coverage, especially for VoIP phones and card terminals.
Common questions
Mesh Wi-Fi or a range extender?
A mesh system is usually smoother because all units work together and devices move between them automatically. A basic extender often creates a separate network and can cut speed.