On 28 April 2025, Lisbon was without power for more than 8 hours. The companies that kept trading had a network with autonomy, internet over independent routes and systems outside the office.
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A lost working day costs more than the infrastructure that would have prevented it. On 28 April 2025 the power went off at 11.33am and Lisbon waited until 8.12pm for it to start coming back. The companies that kept invoicing had three things: network infrastructure with autonomy, internet over independent routes and critical systems outside the office. This guide shows how to set that up, and how to sum it all up on a single sheet.
For most SMEs, the honest answer was "not even an hour". Server down, fibre without signal, landlines silent and nobody with the authority to decide. It was not bad luck: it was lack of preparation.
| Time | Fact |
|---|---|
| 11.33am (Lisbon) | Mainland Portugal and Spain go dark. ENTSO-E dates the event at 12.33pm CET. |
| Afternoon of the 28th | The Government holds an extraordinary meeting and declares an energy crisis (in force until 11.59pm on the 29th). The system restart is driven from Castelo do Bode and Tapada do Outeiro. |
| 7.25pm | First customers reconnected in Porto (figures from the E-Redes chairman to Parliament). |
| 8.12pm | Restoration begins in Lisbon. |
| Midnight | Around 95% of customers already have power. |
| 3am on the 29th | Supply fully restored. |
In its report to the Government, the communications regulator called for an assessment of operators' battery and generator autonomy and for minimum standards for network equipment. If the operators themselves run out of battery, your "backup internet" does too.
Powering 40 desktops for an entire afternoon is a waste. What matters is the core: the network, the link to the outside world and the systems where the work lives.
| Element | Impact if it stops | Measure |
|---|---|---|
| Router, firewall, core switch and access points | Laptops lose the network | A UPS dedicated to the network, sized for hours, not minutes |
| Internet access | No email, cloud or clients | Fibre + an independent alternative route (another operator, 4G/5G, ideally satellite) |
| Files and applications | Team without documents | Hosting in the cloud or a data centre; if there is a local server, UPS with automatic shutdown |
| Voice | Clients cannot get through | Cloud PBX with mobile app and call forwarding |
| Laptops and smartphones | Mobility lost | Charged batteries, power banks and VPN set up in advance |
A UPS takes over the load the millisecond the mains fails. It has two jobs: keeping the essentials alive and shutting servers down without corrupting data. Autonomy is defined by the objective (a 10-minute model will never deliver 8 hours) and by the short list of equipment that really matters.
Example: 25 employees on laptops and a file server in the office. One UPS serves only the router, firewall, core switch, two APs and the satellite dish. Another, dedicated to the server, shuts it down cleanly after 15 minutes. The team keeps email and cloud for the full planned autonomy; the server comes back intact. The investment is a fraction of what protecting the whole floor would require.
Redundancy only exists if the links share no single point of failure. Two fibres from the same operator through the same duct are one connection with two contracts.
More detail in the guide to internet bandwidth and redundancy for businesses.
ReStream (a US technology company and a world reference in multi-platform live streaming) entrusted DataRoad with its Cascais office. A core of Layer 3 PoE switches, Wi-Fi 6, an enterprise firewall, a satellite link as a redundant route and continuous monitoring, under an IT Unlimited contract. In a business that lives on live broadcasts, losing the internet is not an academic hypothesis. In an SME it should not be either.
And we apply the same recipe to ourselves. The DataRoad data centre runs on redundant internet connections, failover and power autonomy; it is where international clients work remotely. It is the foundation of our remote working solutions for companies that need to operate with the office closed.
An effective continuity plan for power cuts fits on a printed A4 sheet:
Without a rehearsal, the plan is a hypothesis. Schedule an annual test: at the end of the working day, cut power to the network and record what fails.
Under an IT Unlimited contract, we calculate UPS autonomy, set up internet redundancy with automatic failover and monitor the equipment: the power-loss alert reaches us before the client's phone call. If operations cannot stop out of hours, Premium 365 extends cover to nights, weekends and public holidays. Head office in Alfragide; support across the whole of Portugal.
In Lisbon, more than 8 hours before restoration began: the cut was at 11.33am and power started returning at 8.12pm, with everything restored by 3am on the 29th. Around 95% of customers had power by the end of the 28th, with big differences between areas.
No, not in a prolonged outage. It covers a cut fibre well, but ANACOM showed that mobile networks also suffered. Satellite on a UPS is the most robust backup.
Only if you need to power heavy loads for many hours. For network and internet over a few hours, a well-sized UPS does the job; local servers, cooling or machinery justify a generator.
No: it eliminates half of it. The data is safe, but without power and redundant internet nobody can reach it.
We analyse UPS, links, critical systems and how the team would work in the dark. We deliver your one-page plan and a prioritised list of fixes. Request a no-commitment proposal.
More than 10 workstations · support contract · remote, on-site and telephone support. +351 211 459 950 * · sales@dataroad.pt
*Call to a Portuguese landline.
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