Weak Wi-Fi in the Office: How to Find and Fix Dead Zones
Practice4 minInnovialabs editorial team
In short
Map the signal with a heatmap survey, then fix dead zones by moving access points to the ceiling near users, tuning channels and transmit power, and adding cabled access points instead of repeaters where coverage is still weak.
The short answer
Dead zones are fixed in two steps: measure first, then change. Walk the office with a free Wi-Fi survey tool to get a signal map, find where the signal is weak or where networks interfere, and then fix placement, channels and power. If that is not enough, add another cabled access point — repeaters usually make things worse.
Why dead zones appear
- Obstacles: concrete and brick walls, metal cabinets, elevator shafts, mirrors and tinted glass absorb or reflect the signal.
- Bad placement: a router in a server cupboard, on the floor or behind a monitor.
- Interference: neighbouring offices on the same channels, especially in the crowded 2.4 GHz band.
- Too much power: a loud access point that phones hear but cannot answer back to.
- Too many clients on one access point in a busy meeting room.
Step 1. Do a heatmap survey
A heatmap shows signal strength on your floor plan.
- Take a floor plan image (a photo of the evacuation plan is enough) and note the scale.
- Install a free survey tool. There are free or free-tier apps for Windows, macOS and Android; some vendors also include survey tools in their controller software.
- Walk slowly along the office and click your position on the plan every few metres.
- Look at the result for both 2.4 GHz and 5 GHz.
How to read the signal (RSSI):
| Signal level | What it means in practice |
|---|---|
| around −30 to −60 dBm | Strong, everything works |
| around −60 to −67 dBm | Good for calls and video |
| around −67 to −75 dBm | Browsing works, calls may break up |
| weaker than about −75 dBm | Dead zone for practical use |
Also check the channel overlap view: several strong networks on one channel are as bad as a weak signal.
Step 2. Fix access point placement
- Mount access points on the ceiling or high on a wall, in the open, not inside cabinets.
- Place them where people work, not where the cable happens to end.
- Keep them away from metal objects, microwave ovens and thick walls.
- Point the device as the vendor recommends — ceiling models radiate downward.
Re-run the survey after each move to see the effect.
Step 3. Tune channels and power
- 2.4 GHz: use only non-overlapping channels 1, 6 and 11.
- 5 GHz: prefer 20 or 40 MHz channel width in dense offices; wide channels look fast but collide more often.
- Give neighbouring access points different channels.
- Lower the transmit power rather than raising it. Moderate power on several points gives better roaming than one loud point.
- Use the controller's automatic channel planning if available, then verify the result with a survey.
Step 4. More access points or repeaters?
| Option | How it works | When it fits |
|---|---|---|
| Repeater (extender) | Receives and re-sends the signal over the air | Temporary fix for a small area |
| Mesh without cable | Points link wirelessly to each other | Where cable is impossible, with a dedicated backhaul radio |
| Cabled access point | Each point has its own Ethernet uplink | The right default for an office |
A repeater uses part of the airtime to talk to the main point, so a client behind it typically gets noticeably less speed and higher latency. For an office, a cabled access point with PoE is the reliable solution.
Step 5. When to run cable
Run a new cable when:
- the survey shows a weak zone that placement and tuning cannot fix;
- the area has many users (meeting room, open space);
- you rely on video calls or VoIP there;
- the "temporary" repeater has become permanent.
One cable to the ceiling usually solves the problem for years, while wireless workarounds need constant attention.
Checklist
- Survey made for both bands and saved for later comparison.
- Access points on the ceiling, near users, away from metal.
- Non-overlapping channels, moderate power.
- One SSID across all points for roaming.
- Weak zones covered by cabled APs, not repeaters.
- Survey repeated after changes and after furniture moves.