A recurring complaint in many cafés: the Wi-Fi is fine when quiet, then falls apart once it's busy. The owner upgrades the internet plan, and nothing changes.
That points to the bottleneck being not bandwidth but the equipment serving it.
Start with device count, not headcount
The most common miscalculation is counting seats. One guest rarely brings one device.
| Guest type | Active devices |
|---|---|
| Quick dining guest | 1 (phone) |
| Working guest | 2–3 (phone, laptop, sometimes tablet) |
| Guest with a smartwatch | +1 |
Add the operational devices people often forget: the till, receipt printer, ordering tablets, card terminal, security cameras, music speakers, and staff phones.
A 40-seat café with half its guests working easily reaches 70–80 active devices at peak. Compare that with a home router designed for around 20.
Calculating the number of access points
Two rules used together, then take the larger:
- By density: one access point per 25–30 active devices
- By area: one access point per 100–150 m² of open space
For an 80 m² café with 70 devices, the area rule suggests one unit, but the density rule suggests three. Take three.
Partitioned spaces change the calculation. Brick walls cut the signal, so an 80 m² space divided into four rooms may need an access point in each even with few devices. The obstructing materials are covered in the router placement guide.
Calculating bandwidth
This is where people overshoot. Real requirements are far smaller than intuition suggests, provided there's per-device limiting.
A sensible calculation:
- Estimate active devices at peak. Say 70.
- Of those, usually only 20–30 per cent are actually sending data at any moment. Say 20 devices.
- Multiply by per-device need. For browsing and social media, 3 Mbps is adequate. 20 × 3 = 60 Mbps.
- Add headroom for operations and spikes. Round to 100 Mbps.
A 100 Mbps plan is adequate for a 40-seat café, provided per-device limits are in place. Without them, one person downloading a large file can consume the entire capacity, however large it is.
Upload capacity matters more than people assume. A guest on a video call sends a video stream upward. An asymmetric plan with 10 Mbps upload fills up quickly with four people in online meetings at once.
Limits worth setting
| Limit | Sensible value | Reason |
|---|---|---|
| Speed per device | 5–10 Mbps | Enough for streaming, stops one person taking everything |
| Devices per guest | 2–3 | Avoids pile-up |
| Session duration | 1–3 hours, or unlimited | Depends on the business model |
| Data cap per session | Optional | Prevents large downloads |
The per-device speed limit is the most influential. Without it, none of the calculations above hold.
Separating the operational network
The till, receipt printer, and security cameras must not sit on the same network as guests. The reason isn't only security but stability: a saturated guest network mustn't cause a failed transaction.
Separation is done via VLANs or a separate SSID with isolation. It's discussed in the guide to separating a guest network.
Business-class equipment: what's different
The price gap between a home router and a business-class access point often makes owners hesitate. What you're really paying for isn't speed but these:
- Client capacity. Designed for 50–100 devices per unit, not 20.
- Central management. Several units configured from one panel, with guests moving between units without dropping.
- Airtime fairness. Slow devices don't hold up others for too long.
- Power over Ethernet. Power and data over one cable, so units can be mounted on the ceiling without a socket.
- Usage statistics. Useful for learning peak hours and visit patterns.
Two worked examples
Small café, 25 seats, 60 m², one room
- Estimated active devices: 35
- Access points: 2 units
- Bandwidth: 50 Mbps, minimum 20 Mbps upload
- Per-device limit: 5 Mbps
Restaurant, 80 seats, 200 m², two floors
- Estimated active devices: 120
- Access points: 4–5 units, at least two per floor
- Bandwidth: 150–200 Mbps
- Per-device limit: 8 Mbps
- Separate VLAN for the till and CCTV
Checking after installation
Don't rely on impressions. Measure at peak hours, not when it's quiet:
- Run speed tests from several points in the space, including the furthest corner.
- Note the number of connected devices in the management panel.
- Watch whether any guests complain, and at which tables.
Complaints clustered in one area indicate a coverage weak spot. Complaints spread evenly at certain hours indicate insufficient capacity. Those two findings demand different actions, and measuring is how you tell them apart.
