“Your Connection Never Works!”: Why Wi-Fi on Spain’s High-Speed Trains Falls Short and How Satellites (Starlink and Kuiper) Could Change the Journey

There are phrases repeatedly uttered like a mantra on the quiet cars of high-speed trains: “No signal,” “Connection dropped again,” “Can’t send the file.” The onboard Wi-Fi is one of Spain’s unresolved issues in the railway sector. And not just for comfort: today, for many, traveling also means working on the move. While neighboring countries have standardized their digital experience onboard trains, in Spain travelers alternate fluid connection moments with shadow zones that turn video calls into an impossible mission. The good news is that technology offers two complementary paths out of the loop: improving ground network coverage along the route and looking to the sky with low-earth orbit satellite constellations like Starlink (SpaceX) or Kuiper (Amazon).

This report explains why Wi-Fi fails on trains, how other European countries are solving the problem, what satellites contribute, and what needs to happen for the connection to stop being a lottery between Madrid and Barcelona, Seville, or Valencia.

Diagnosis: fast trains, fragile signals

At 300 km/h, coverage depends not just on “bars on the phone.” Three factors interfere badly with high speeds:

1. . High-speed lines pass through rural and low-density areas, with fewer antennas and larger cells. Additionally, there are tunnels, viaducts, and narrow sections that hinder signal propagation.
2. Train physics. The metallic enclosure of train cars acts as a Faraday cage. While the exterior receives LTE/5G signals, inside the carriage, mobile devices struggle for crumbs. That’s why serious systems install antennas on the roof and interior repeaters.
3. Limited backhaul. Onboard Wi-Fi isn’t magic: it aggregates mobile (and/or satellite) links to share throughout the train. If the track only offers a few Mbps—because the cell is saturated or distant—then the entire train gets bottlenecked. The ping increases, useful throughput drops, and the connection “fades in and out.”

Adding to this is the mobility management: over long routes, the train “hops” between cells every few seconds. Each handover can cause micro-interruptions, and the more users connected simultaneously, the higher the probability of frozen video calls.

Europe: the lesson of the track (and tunnels)

France and Germany, with comparable high-speed networks, understand that terrain matters as much as the train router. The most stable solutions combine:

• Trackside networks designed for trains (multi-operator LTE/5G or neutral networks), with sector antennas aimed along the route and denser cells.
• Infrastructure inside tunnels (radiating or “leaky feeder” systems) to prevent signal loss at each penetration.
• Onboard units with exterior antennas and interior repeaters, serving as a “window” outward and distributing signal inside.

Not everything is perfect—neither in TGV nor in ICE trains—but the average experience becomes more consistent: the traveler can open their laptop and, without thinking, work. In Spain, the situation is more heterogeneous: multiple railway operators, varied coverage depending on the route, and a greater reliance on the general mobile network in tricky segments. The result is a widespread feeling: “it works sometimes.”

Two complementary paths: strengthen ground networks and harness the sky

If recent years have taught us anything, it’s that there’s no silver bullet. The most convincing approach among engineers combines ground network and satellite solutions:

1) More ground network where needed (and better prepared for trains)

• Densify LTE/5G coverage along tracks with closer cells and aimed at the railway corridor.
• Use multi-operator aggregation: enabling the train to communicate with multiple networks simultaneously and dynamically select the best.
• Equip critical tunnels with radiant systems to maintain signal stability underground.
• Adopt the upcoming FRMCS (the 5G successor to GSM-R) for railway services and, in parallel, open commercial capacity for onboard Wi-Fi.

Advantages: low latency and consistent bandwidth when deployment is good. Disadvantages: high CAPEX in long, sparsely populated segments, and project timelines that don’t match users’ “connectivity now” expectations.

2) LEO constellations as a “second lung”

Low Earth Orbit (LEO) satellites have changed the game. Unlike traditional geostationary satellites (35,786 km), LEOs operate at 550–1,200 km, with much lower latencies and electronically steered antennas that track the train and “tilt” the beam in real time. Two programs gather attention:

• Starlink (SpaceX): already offering mobility services for airplanes and ships, with hardware designed for moving vehicles and agreements with airlines. Its mesh architecture (including laser inter-satellite links in advanced versions) reduces dependence on ground stations.
• Kuiper Project (Amazon): still in deployment, with next-gen satellites and a supply chain drawing from Amazon’s cloud experience. Its promise involves low-profile terminals, cost-effective solutions, and seamless integration with cloud services.

Advantages: coverage over remote segments, viaducts, and zones where erecting towers isn’t feasible. Disadvantages: tunnels and trenches still pose a challenge (no line of sight); integration with ground networks and compliance with regulations (such as spectrum use, authorizations, gateways locations) must be managed.

How satellites fit into a real train

The image familiar to technicians isn’t of the laptop talking to space, but of an onboard computer that chooses the best path at each moment:

1. Low-profile satellite antenna (phased-array) mounted on the roof, with dual terminals for redundancy if needed.
2. Multi-operator 4G/5G modem with multiple SIMs and exterior antennas.
3. Controller aggregating backhaul (satellite and terrestrial) and deciding: if the terrestrial cell is strong and low latency, prioritize it; if the train enters a shadow zone, switch to satellite to maintain continuity.
4. Indoor Wi-Fi with access points per carriage, quality of service (QoS), and fair use policies to ensure 300 passengers don’t turn the train into a “speedtest fair.”

The experience won’t be identical to home fiber — peaks in consumption and handovers will persist — but it will be predictable: video calls will stop depending on a miracle in the middle of the plateau.

Comparison of options: pros and cons at a glance

Why is Spain “a step behind”?

Spain has the most extensive high-speed network in Europe. Paradoxically, this strength complicates connectivity: more kilometers through less populated areas = more investment needed to ensure a good digital experience “end to end.” Added to this is a market with multiple railway operators (public and private), each with their own onboard solutions, and an ecosystem where coordination with telecoms and administrations is key. Unlike other countries with more concentrated corridors, Spain needs to normalize services across many lines.

The leap isn’t just about replacing routers. It involves sharing infrastructure agreements, trackside projects, and yes, contracts with satellite providers that enable a robust hybrid system without skyrocketing costs.

What needs to happen for travelers to notice it “for real”?

1. Public roadmap. Operators and authorities should explain what will be done along each corridor: more 5G cells, radiants in critical tunnels, LEO pilots, deployment schedules, and quality goals (latency, availability).
2. Serious LEO pilots. Select routes with “black zones” and test Starlink (operational) and Kuiper (when ready), measuring continuity, ping, throughput, and costs. Publish results and lessons learned.
3. Hybrid contract. It’s not a matter of “land or satellite”: it’s both. A bidding document that requests smart switching, SLA for continuity, and clear usage policies to prevent abuse.
4. Honest communication with travelers. Set expectations about what to expect (and what not): video calls yes, but perhaps not 300 people streaming 4K simultaneously. Managing expectations also improves the experience.

Meanwhile, tips for travelers

• Download documents and series before boarding; use Wi-Fi for email, messaging, and video calls, not for syncing large files.
• 4G/5G tethering as a backup plan: sometimes your mobile (with good data plan) performs better than shared Wi-Fi.
• Choose your carriage: in some trains, sitting near the roof or close to certain equipment improves signal; ask train staff.
• Avoid rush hours if you need to upload large files: network congestion is real.

Conclusion: moving bits at train speed

Spain has shown it can move people at 300 km/h reliably. Now it’s time to prove it can move bits at a predictable speed onboard. The technology exists; the options—ground, sky, or both—are available too. It will require investment, clear priorities, and well-measured pilots. For travelers, the difference between a “Wi-Fi-enabled” train and a train with “real connectivity” isn’t just semantic: it’s what separates a journey from being lost to three hours of productive work.

Frequently Asked Questions

Why does Wi-Fi often fail on high-speed trains in Spain?
Because combining 300 km/h with rural zones, tunnels, and few antennas is challenging. If the train solely relies on the general mobile network, interruptions, high latency, and throughput drops occur. The solution involves more trackside network and/or adding satellites as a second lung.

Do Starlink or Kuiper work inside tunnels?
No, satellites need a line of sight. Inside tunnels, radiating systems or dedicated networks are necessary. The satellite’s value lies in viaducts, remote zones, and when ground network fails.

When will these solutions be available?
Starlink already provides mobility services (planes, ships, vehicles) and can be piloted on trains with proper authorization. Kuiper is deploying. Actual availability in Spain depends on contracts, tests, and regulation.

Can “home internet” be achieved on the train?
Much improvement is possible (stable video calls, smooth browsing), but the congestion will persist: hundreds of users share the same “pipe.” With a well-designed hybrid architecture, the leap in quality is very significant.

Sources: public communications from European railway operators on onboard connectivity; technical documentation from UIC and sector organizations on railway networks and FRMCS; public information from Starlink (SpaceX) and the Kuiper Project (Amazon) on mobility services and LEO constellations.