The ISP's router
or your own?

Yes, and it's the right way to do it with practically any fibre provider, whether Movistar, Orange or another. The usual approach isn't to unplug the provider's router and simply swap it out, but to put it in bridge mode — sometimes called something else depending on the provider — and connect yours behind it. In that mode, the provider's box still authenticates and terminates the fibre line, while your router takes over handing out Wi-Fi, applying firewall rules and organising the internal networks. What you must avoid is plugging your own router in behind the provider's without enabling bridge mode first, because you then have two routers in cascade each doing its own address translation, and that's exactly what later stops cameras being visible from outside or makes certain services fail in ways that are hard to diagnose. Each provider names and enables that mode differently, so it's worth confirming before treating the change as done.

It's the configuration in which the provider's box stops behaving as a full router and limits itself to being the way in: it receives the fibre and passes that bandwidth to a second device, which hands out IP addresses, manages the Wi-Fi and applies the network rules. Without bridge mode enabled, if you connect your own router behind the provider's, both keep acting as routers at the same time, which creates what's known as double NAT: two successive address translations that almost no service expects. In practice that's what breaks very specific things, such as a camera that can't be viewed from outside the house even though it's set up correctly, a network printer that behaves erratically, or certain incoming connections that simply never reach their destination. Enabling bridge mode is the step that prevents all of that from the outset, which is why it should be done before anything is considered installed.

Yes, and that's exactly the point of enabling bridge mode: the provider's Wi-Fi is switched off, and the wireless network depends entirely on your own router or access points. It isn't an unwanted side effect, it's the aim of the change, because having two Wi-Fi networks running at once — one from the provider and one from the added router — is precisely the situation to avoid. If bridge mode isn't enabled and the new router is simply plugged in while the provider's keeps broadcasting its own network, the usual result is confusing for anyone using the home or premises: two networks with similar names, devices connecting to the wrong one, and nobody quite sure why something sometimes doesn't work. With bridge mode done properly, only one Wi-Fi network is visible — yours — and it's easier to explain to the people who use it and to maintain afterwards.

Sometimes, yes, and it's one of the reasons we don't recommend simply getting rid of the provider's router. Some TV set-top boxes and VoIP landlines are designed to work connected directly to the provider's router, and depend on internal settings that box applies without the user seeing them. That's why the sensible approach isn't to replace the whole box, but to put it in bridge mode for data and, if necessary, reserve a specific connection or VLAN so the TV box or phone keeps talking to the provider's router as it always has. Anyone who suggests swapping it and that's that, without first asking whether you have TV or a landline on that line, hasn't checked the bare minimum before making that recommendation — and it's exactly the kind of detail that turns into a TV that stops working on the same day the new router goes in.

No, and it's one of the most expensive myths to buy into for no reason. A more powerful or more expensive router in the same old corner still has the same underlying problem: the Wi-Fi signal doesn't get through thick walls or long distances much better because it has a flashier logo or a higher price. If the Wi-Fi reaches a particular room, another floor or an area far from the router badly, that's a coverage problem, not one of processing power or advanced features that in practice hardly anyone uses in a normal home. The real fix is adding well-placed access points or nodes, or running cable where you can, not swapping the box you have for a pricier one in the same spot. Before buying anything, it's worth measuring where the signal actually fails and counting how many obstacles are in the way, because that's what determines the solution, not the router brand.

Hardly ever, if we're talking about a normal flat used mostly for browsing, streaming and giving phones and the computer a good connection. The provider's router, well placed in a central spot and without a pile of cheap repeaters that actually complicate things more than they help, usually covers a standard-sized home comfortably. Your own router starts to make sense when needs appear that the rented box isn't designed for: cameras that need to be viewed reliably from outside, a VPN for working securely from home, a separate guest network that doesn't touch the main one, or simply premises or a small business where the demands are no longer those of a home. If none of those situations rings a bell, changing the router won't improve anything that matters, and the time spent configuring it is probably better invested elsewhere — such as fixing a coverage problem, if that's what's really failing.

Yes, in a business it's usually worth having at least your own firewall behind the provider's router, even if you don't always need to replace the box entirely. What changes compared with a home is the list of needs: you want firewall rules you can adjust yourself, a VPN for secure remote access, network segmentation so the card terminal doesn't share space with the customer Wi-Fi, and dual WAN to keep the business connected on the day the main fibre goes down — something that isn't optional in many sectors. The provider's rented router isn't designed for this: it's fine for browsing, but it doesn't offer the control or separation that a business with a till, customers and sensitive data needs. Here the change isn't a technical whim, it's stopping a network fault from becoming a security problem or lost trading hours, and it's best tackled before it happens, not after.

Yes, and the real work isn't picking the most expensive router in the catalogue, but enabling bridge mode correctly and leaving the installation working with no loose ends. That means confirming with the provider how the mode is enabled in your specific case, checking the line works just as well once the change is made, and configuring the router or firewall behind it with the networks, rules and access you need. If you have TV or a landline on the same line, that's checked before touching anything, and planned so neither service drops on the day of the change — either by keeping that function on the provider's box or reserving the connection it needs to keep working. What we don't do is swap one box for another without looking at what depends on it, because that's exactly the mistake that leaves someone without TV or a landline without seeing it coming.