The Bandwidth Walk-Through: Checking a Flat’s Internet Before You Sign

There’s a particular kind of disappointment that comes from moving into a flat and discovering the second bedroom is a mobile-signal black hole, or that the “fibre broadband” promised in the listing is actually a tired copper line doing its best. You can’t always tell from a viewing, but you can usually tell enough. And in 2026, with more of us working from home at least part of the week, connectivity is not a nice-to-have. It’s part of the rent’s actual value.

The good news is that you don’t need to turn up with a signal meter and a clipboard. A phone, a few pointed questions, and five minutes of deliberate checking will tell you more than any agent’s enthusiastic adjective.

Start with the postcode, not the patter

Before you even set foot in the flat, run the postcode through Ofcom’s broadband checker and a couple of the major providers’ own availability tools. You’re looking for two things: what technology is available, and what speed is realistic. “Full fibre” or “FTTP” is generally the gold standard. “Part fibre” or “FTTC” usually means fibre to the cabinet, then copper to the building — which can be fine, but it’s more distance-sensitive. If the checker shows only standard broadband, treat any listing claim of “ultrafast” with deep suspicion.

It’s also worth checking whether the building is on a specific network. In parts of the UK, CityFibre, Hyperoptic, Virgin Media and Openreach all build differently, and not every block is wired for every provider. A flat can be in a “fibre-enabled” area and still not have fibre into the actual building. The checker gives you the theory; the viewing gives you the reality.

The five-minute phone test

At the viewing, walk the flat with your phone in hand. Don’t just glance at the signal bars in the hallway. Go into each room you’d actually use — bedroom, living room, kitchen, and that awkward box room you’ll claim will be a study. Switch off Wi-Fi so you’re testing the mobile network, and check both data and call signal. If you’re on EE, O2, Vodafone or Three, remember that coverage varies by network; a flat that’s useless on one can be perfectly fine on another.

Try a quick speed test on mobile data. It doesn’t need to be scientific. If a page loads slowly or a short video stalls, note it. Then try a call — not just a WhatsApp call, but a normal voice call if you can. Basement flats, conversions with thick walls, and buildings with metal-framed windows are classic dead-zone candidates. So are new-builds with lots of insulation and foil-backed materials, which can be brilliant for energy bills and rubbish for signal.

If the flat has Wi-Fi already

Sometimes the current tenant or landlord has left a network running. Use it. Ask permission, connect, and run a speed test from more than one room. Standing next to the router proves nothing except that the router works. The real question is whether the signal reaches the sofa, the desk, and the bedroom without a mesh system.

Look at where the router sits. Is it in a cupboard? Behind a TV? In the hallway because that’s where the phone line comes in? These are all common, and all mildly annoying. If the flat is long and thin, or has a galley kitchen and a rear bedroom, ask whether a booster or mesh kit has been needed. A landlord who says “it’s fine everywhere” without ever having lived there is not a reliable source.

Ask these questions (and listen for the dodge)

The useful questions are specific. “What broadband is in the flat?” is better than “Is the internet good?” Ask who the current provider is, what package speed they pay for, and whether the building has fibre to the premises or just to the cabinet. Ask if there’s a phone line, an ONT box, or a coaxial point. Ask whether the landlord pays for broadband or whether you set up your own contract. If it’s included in the rent, ask what happens if it’s too slow — and get the answer in writing if it matters to you.

If the agent doesn’t know, ask them to find out. A vague “superfast is available” is not an answer; it’s a marketing phrase. You want the provider name and the technology type. If the landlord has never lived in the flat and has no idea, that’s not automatically a red flag, but it does mean you should rely on your own checks rather than their assurances.

Red flags worth walking away from

No mobile signal in the main bedroom and no realistic way to fix it is a serious issue if you work from home or need to take calls. A flat that only has standard broadband in 2026, with no fibre planned, is a hard sell for anyone who streams, games, or Zooms. A landlord who gets defensive when you ask about broadband is telling you something about how future maintenance requests will go. And a listing that promises “superfast” without naming a provider or technology is usually hoping you won’t ask.

One more thing: check the communal areas. If your mobile signal dies in the stairwell, that’s where your delivery driver will try to call you. If the building has a shared meter cupboard or a basement bike store with no signal, note it. These small dead zones add up.

The final sanity check

Before you leave, stand by the window in the room where you’d most need decent internet and run one last speed test. Take a screenshot. It’s not a contract, but it’s evidence. If the flat ticks the boxes on space, rent and location but fails the connectivity test, don’t talk yourself into it. Buffering is not a personality trait, and a dodgy Wi-Fi signal is much harder to fix than a wobbly shelf.

A five-minute check won’t guarantee perfect broadband, but it will stop you signing a tenancy based on an agent’s hopeful phrasing. And in the flat-hunting game, that’s worth more than a shiny kitchen island.