Plan for the peak, not the average. Give tickets and payments their own networks with guaranteed priority, and a backup connection that takes over automatically and carries only business traffic. Know exactly what your card terminals and ticket scanners do offline, and agree limits with your payment provider in advance. Test everything under load before doors open, and agree who's on site and who to call. Most event-day failures are predictable.
What actually fails first on an event day?
Event-day failures rarely come out of nowhere. They're usually the weakest part of the setup meeting its heaviest load. These are the most common weak points, in roughly the order they bite.
| Weak point | Why it fails on the day | The fix |
|---|---|---|
| One shared internet line | Guest phones uploading photos and video, CCTV and payments all compete for the same upload capacity | Size for the peak, cap guest traffic and give payments and ticketing priority |
| WiFi at pinch points | Gates, bars and concourses hold hundreds of devices on a few access points | Extra access points where crowds bunch, planned from a survey |
| Guest network address pool | The network runs out of addresses to hand out, so new phones can't connect | Size the pool and shorten lease times for event traffic |
| Card terminals on guest or flat WiFi | Congestion delays authorisations, queues build and staff switch to cash they don't have | Terminals on the payment network or their own SIM |
| Ticket scanners | Flat batteries, out-of-date apps and handsets that never synced the latest sales | Charge, update and sync the day before; spares on the gate |
| 4G/5G backup | The crowd itself fills the local mobile masts, just when the backup is needed | Test failover on a busy day; keep backup traffic to essentials |
| Power | A tripped circuit takes down the switch that serves the bars | Know what's on each circuit; small UPS units on key network kit |
Most of these come back to one design flaw: everything sharing one network and one connection. Our guide explains how to design venue WiFi and separate networks. This article is about the day itself.
How much capacity do you need on the day?
Work it out from the people and the systems, not the building.
Example: a 3,000-capacity venue assumes that a quarter of the audience connects to guest WiFi at the same time. That's 750 devices. With each guest capped at 2Mbps, guest traffic could reach 1.5Gbps if everyone used it at once, which in practice they won't. The venue sets a total guest cap well below the line speed, and reserves guaranteed capacity for 40 card terminals, six ticket scanners, the box office and CCTV. The numbers are an illustration. The method is what matters: estimate the peak, cap the guests and protect what earns money.
Upload matters more than most venues expect. Card payments are tiny, but CCTV, live streams and a crowd posting video all send data out. That's one reason venues of any size suit a leased line, with the same speed in both directions and a guaranteed fix time. See what a leased line is and when to use one.
How should failover work?
A 4G or 5G router that takes over automatically when the main line fails is standard. On an event day, three details decide whether it helps.
It must carry the right traffic. A backup connection can't carry a full crowd's guest WiFi. Set it up so that, on failover, payments, ticketing and the box office keep running and guest WiFi is throttled or paused.
It may share the crowd's mobile network. Thousands of phones in and around the venue use the same local masts. So do card terminals that connect over their own SIM. Check which networks your backup router and SIM terminals use, and consider putting them on different networks, so one congested network doesn't take out both.
It must be tested for real. Unplug the main line on a busy day, not a quiet Tuesday, and watch what happens at the tills and the gates.
What happens to card payments if the connection drops?
It depends on your payment provider and the settings on your terminals. Check before the event, not during it.
Since 2017, Visa has set a "zero floor limit" for UK contactless payments, which means every contactless payment has to be authorised online by the card issuer (ACS). So when a terminal loses its connection, contactless is usually the first thing to stop.
Some providers offer an offline or "store and forward" mode. The terminal accepts the payment, stores it and sends it for authorisation once it's back online. It's useful, but it comes with conditions. Adyen's documentation, for example, says the merchant is "fully liable for the risk of failed captures, chargebacks, and disputes" on offline payments, and requires limits per transaction and on the total stored. Contactless may be blocked while offline, forcing chip and PIN.
Ask your payment provider four questions: is offline mode available on our terminals, is it switched on, what are the limits, and who carries the risk of a declined payment? Terminals with their own SIM avoid your network entirely, which helps, as long as the mobile network isn't the thing that's struggling. The security side of payments is covered in our chapter on PCI DSS for venues.
Can ticket scanners work offline?
Many scanning apps can validate tickets offline if the ticket list has been downloaded to the device first. The catch is that scanners working offline can't see each other's scans, so a copied or screenshotted ticket could get in twice until the devices sync again. Ask your ticketing provider how its app behaves offline, how often it syncs, and whether late sales reach the scanners without a connection. Then do the obvious things: charge every device, update the app and sync the list the day before, and keep spares at the gate.
Who needs to be on site?
Decide this in writing before the event. Someone on site should know where the network cabinet is, what each light means and how to restart the equipment safely. Keep one sheet at the box office with the support numbers for your IT provider, internet provider, payment provider and ticketing platform, and the account numbers each will ask for. For your biggest events, arrange for an engineer to be on site or on call.
Pre-event checklist
| When | What to check |
|---|---|
| 4–6 weeks before | Expected crowd and layout; temporary bars, fan zones or outdoor stages that need network points; extra access points, lines or terminals ordered; on-site cover booked |
| 1 week before | Failover tested under load; guest caps and priority for payments and ticketing confirmed; offline settings confirmed with payment and ticketing providers |
| The day before | Scanners and handheld terminals charged, updated and synced; spares labelled; firmware updates paused so nothing restarts mid-event |
| 2 hours before doors | Test payment at every till; test scan at every gate; check the guest WiFi from the busiest spot |
| During | One person watching the network and payments, with a direct line to support |
| After | Note what slowed down, where and when; fix it before the next event |
How Indigo does this. Indigo Unified Communications delivered stadium WiFi, connectivity and a telephony upgrade for Falkirk Football Club, with WiFi across the 8,000-seat stadium designed for match-day crowds and separate networks for club staff, operations and guests. At SWG3 in Glasgow, guests, staff and payment systems each have their own network so busy nights don't affect the tills. Gold and Platinum clients get 24/7 monitoring, fibre Ethernet leased lines have a 5-hour fix time, and out-of-hours and event-day engineer cover is available by arrangement, at extra cost. Venue WiFi and connectivity →
What to do next
- List every system that must work on the day (tills, terminals, scanners, box office, CCTV, phones) and how each one connects.
- Ask your payment provider and ticketing provider exactly what happens offline, and get the answers in writing.
- Book a failover test during a real event, with someone watching the tills and gates.
- Agree event-day cover and escalation with your IT provider before your next big date.
- Run our venue technology readiness checklist to find the gaps.
Frequently asked questions
Why does venue WiFi slow down when it's busy?
Usually because too many devices share too few access points, or because guest traffic is using the same internet connection as everything else with no limits. The fix is more access points where crowds gather, a cap on each guest's usage, and priority for payments and ticketing. A faster line alone rarely solves it.
Can card machines work without internet?
Some can, depending on your payment provider. Offline or "store and forward" modes accept a payment and authorise it later, but the merchant usually carries the risk if it's declined, and limits apply. Contactless normally needs online authorisation. Terminals with their own SIM keep working if your venue's line fails.
Is 4G or 5G backup enough for an event venue?
It's enough to keep payments, ticketing and the box office running while the main line is repaired, if it's set up to carry only that traffic. It won't carry a full crowd's guest WiFi, and the crowd may congest local masts. Test it during a busy event and check coverage at your exact venue.
How far ahead should we plan IT for a big event?
Four to six weeks for anything new, such as temporary bars, outdoor stages or extra terminals. New leased lines take much longer, typically 30–90 working days, and a managed 4G/5G connection is usually live within 2–3 working days. Test everything at least a week before the event.
Sources: ACS (Association of Convenience Stores), Changes coming to Visa contactless payments, August 2017 (https://www.acs.org.uk/news/changes-coming-visa-contactless-payments) · Adyen, Offline payments (documentation, accessed September 2026) (https://docs.adyen.com/point-of-sale/offline-payment)
Related: How do you design WiFi and networks for a busy venue? · How do venues keep card payments secure and PCI DSS compliant? · What is a leased line and when should you use one? · Business connectivity
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