The Two Mistakes Offices Make with Wi-Fi
There are two common failure modes in office Wi-Fi design, and they produce similar symptoms despite being opposite problems.
Too few APs, placed for coverage rather than capacity: One access point in the centre of the floor covers the whole office — signal everywhere, but 60 devices competing for airtime on a single radio. Every device gets a weak share of the available bandwidth. Performance degrades under load exactly when everyone needs it most: 9am when staff arrive, midday video calls, 4pm crunch time.
Too many APs placed too close together: Counterintuitively, too many access points cause interference. If neighbouring APs are transmitting on overlapping channels, they create co-channel interference that degrades throughput for every device in range. More APs does not mean better Wi-Fi — correct placement and channel planning are what determine performance.
Designing a Wi-Fi network correctly means optimising for both coverage and capacity, which requires knowing how many devices will connect, what they'll be doing, and what the physical environment looks like.
The Two Things APs Actually Provide: Coverage vs. Capacity
| Coverage | Capacity | |
|---|---|---|
| What it means | Signal reaches the location | Enough bandwidth for all devices at that location |
| How you test it | Signal strength (dBm) — a phone showing 4 bars | Throughput test under real load — speed test with 20 devices connected |
| What limits it | Distance, walls, interference | Number of devices per AP, channel utilisation |
| Common misconception | "Signal is strong everywhere" = good Wi-Fi | Irrelevant if all devices are on one AP |
Most offices have adequate coverage. The bottleneck is capacity. A single Ubiquiti U6 Pro AP can theoretically handle 300+ client connections — but the maximum practical throughput of that AP is roughly 2.4Gbps across all radios. If 60 devices are connected and half are doing Teams calls, you've already consumed most of that budget. Add file syncs, OS updates running in the background, and you'll see degradation.
How to Calculate How Many APs You Need
A practical sizing exercise has three inputs: office area (m²), device count, and traffic profile.
These are starting points, not final answers. The table assumes open-plan offices with standard 2.7m ceilings and a mix of laptops and phones on 5GHz. Adjust upward for: meeting rooms with frequent video calls, concrete or brick internal walls, high-density areas like boardrooms, or warehouses with metal racking.
The 5GHz Rule: Why Channel Planning Matters
The 5GHz band has up to 24 non-overlapping 80MHz channels in Australia. This sounds like plenty — but the practical constraint is that most enterprise deployments limit to 3–4 channels to ensure clean handoff between APs. If you have 8 APs all on the same 3 channels, neighbouring APs interfere with each other unless transmit power is carefully controlled.
The solution is a combination of:
- Reduced transmit power per AP: Rather than each AP blasting at maximum power (which causes it to reach far beyond its intended coverage zone and interfere with neighbours), APs are set to the minimum power needed to serve their area. This requires survey or auto-tuning.
- Auto channel assignment: Both Ubiquiti and Aruba have automatic radio resource management (RRM) that assigns channels dynamically and adjusts power. Aruba's RRM is more sophisticated — particularly in high-density environments.
- 6GHz (Wi-Fi 6E) for high-density: Wi-Fi 6E adds the 6GHz band with 7 additional 160MHz channels. For environments with 50+ concurrent devices per AP, 6GHz significantly reduces contention. Aruba AP-635 and Ubiquiti U6 Enterprise both support 6GHz.
How Walls and Office Layout Affect AP Placement
Key placement principles illustrated above:
- APs are placed to serve specific zones — not in the centre of the entire floor serving everything at once
- Meeting rooms get dedicated AP coverage because a single boardroom video call can saturate a shared AP's capacity
- AP coverage zones overlap just enough for seamless roaming (around 15–20% overlap), not so much that they interfere
- Server rooms don't need an AP — they have wired connections. APs near servers add RF noise without benefit.
The Four Factors That Change the Calculation
A standard plasterboard wall attenuates 5GHz signal by roughly 3–4dB. A concrete wall attenuates by 10–15dB. In an office with solid internal walls (common in older Melbourne CBD buildings), you often need an AP per enclosed room rather than one AP per open zone.
APs are typically mounted on ceilings and radiate downward. A 6m warehouse ceiling means the AP is further from devices than intended, and the signal footprint on the floor is wider — meaning more interference between APs. High-ceiling deployments usually require directional APs and more careful placement.
A Teams call uses approximately 1–3Mbps per participant depending on video quality. 10 simultaneous calls from one AP zone consumes 10–30Mbps — manageable. But if 30 people in an open plan are all on calls simultaneously, that's 30–90Mbps of sustained real-time traffic from a single AP zone. Design for peak concurrent load, not average.
Older 2.4GHz-only devices (some IoT sensors, older printers, legacy equipment) force an AP to maintain a 2.4GHz radio that all nearby devices must share. If you have many such devices, the 2.4GHz band becomes congested regardless of how well the 5GHz network is designed. Segment older devices onto their own VLAN and AP if possible.
When to Choose Ubiquiti vs Aruba for Your Office Wi-Fi
| Scenario | Recommendation | Why |
|---|---|---|
| Open plan, 5–30 staff, standard ceilings | Ubiquiti U6 Pro | Excellent performance-to-cost ratio for this density |
| 30–80 staff, mix of open plan and meeting rooms | Ubiquiti U6 Enterprise or Aruba AP-505 | Tri-band with 6GHz for meeting room capacity |
| 80+ staff, high-density open plan | Aruba AP-515 or AP-535 | Advanced RRM, better per-client scheduling under load |
| Medical or clinical environment | Aruba AP-505/515 | NAC integration, reliable roaming for clinical devices |
| Warehouse with high ceilings | Aruba AP-555 or Ubiquiti U6 Mesh Pro | Higher gain antennas for high-ceiling coverage |
The Simple Rule of Thumb
If you want a quick sanity check without running a full RF survey: plan for one AP per 15–20 concurrent active devices in an open-plan space, with at least one dedicated AP for each enclosed meeting room used for video calls. Then add 20% for growth.
A 40-person office with 4 meeting rooms would typically need 3–4 APs for open plan + 4 APs for meeting rooms = 7–8 APs total. That's a higher number than most people expect, but it's what delivers reliable Teams calls across the whole office simultaneously.
The right answer for your specific space requires a proper design — floor plan, wall materials, device count, and traffic profile. If you're planning a new office fit-out or Wi-Fi refresh, we'll do that assessment as part of the project.