Business Broadband Explained: Fibre vs Leased Line

At some point most growing businesses hit the same question: is our internet connection good enough, and should we be paying for something better? Usually it surfaces when calls drop, a cloud backup crawls, or the whole office slows down at 10am. The choice almost always comes down to two options — full-fibre broadband, or a leased line. They sound similar and the price gap is large, so it’s worth understanding what you’re actually buying.

This guide explains the real differences — speed, symmetry, contention and SLAs — and gives a clear recommendation for who should choose which. We’ll deal in principles rather than exact prices, because the right answer depends on how many people you have and how much of your work depends on the connection staying up.

Full-fibre broadband (FTTP)

Full-fibre — often called FTTP, fibre to the premises — runs fibre-optic cable all the way to your building rather than to a green cabinet down the road. That’s what makes it fast and reliable compared with older part-copper connections. For most small offices it’s plenty.

The strengths are cost and availability. It’s affordable, it’s rolling out across South London and Surrey, and it usually installs within a couple of weeks. Speeds are high for everyday work: email, Microsoft 365, web apps, a normal amount of video calling.

There are two catches. First, it’s usually asymmetric — download is fast, upload is much slower. That’s fine for browsing, less fine for pushing big files up to the cloud. Second, it’s a shared, contended service: you share capacity with other users nearby, so speeds can dip at busy times. And if it goes down, you’re relying on a standard consumer-grade fix, which can mean days rather than hours.

Leased lines

A leased line is a dedicated connection reserved entirely for your business. Nobody else shares it. That single fact drives everything people like about it.

• Symmetric speed — upload matches download. Backups, large file transfers and hosting calls all run smoothly.
• No contention — the speed you pay for is the speed you get, at 9am or 5pm.
• A real SLA — a written uptime guarantee and a fix time usually measured in hours, often with compensation if it’s missed.

The trade-offs are cost and lead time. A leased line costs several times more than fibre broadband, and installation can take weeks or occasionally months because physical work is often needed. You’re paying for a guarantee and dedicated capacity, not just a bigger number.

Fibre vs leased line at a glance

	Full-fibre broadband	Leased line
Speed	Fast download	Fast, symmetric
Upload	Slower than download	Same as download
Shared or dedicated	Shared / contended	Dedicated to you
SLA / fix time	Little to none; days	Strong; hours
Cost	Low	Several times higher
Install time	Days to weeks	Weeks to months

So which is worth it?

Start from how much your business depends on the connection, not from the headline speed.

Full-fibre broadband is the right call for most small businesses. If you have a handful of staff, work mostly in the cloud, and a couple of hours offline would be annoying rather than catastrophic, fibre gives you the speed you need at a sensible price. Spending leased-line money here is over-buying.

A leased line earns its cost when downtime genuinely hurts. Consider it if any of these are true: you rely on constant uptime to trade or take orders; you move large files or run heavy cloud backups every day; you have enough people that contention bites at busy times; or you run VoIP phones and video calls that can’t tolerate the connection wobbling. In those cases the SLA and the symmetric speed aren’t luxuries — they’re the point.

A middle path suits a lot of businesses: run full-fibre now, and keep a leased line in mind as you grow. Many also keep a second connection — a 4G or 5G backup, or a cheaper broadband line — so the office stays online if the main one fails. That’s often smarter than paying for the top tier and having no fallback at all.

Whichever you choose, the connection is only half the job. A fast line into a poorly built network still gives you dead spots and slow days. Getting the wiring, switches and Wi-Fi right is what turns raw speed into a network that actually feels fast at every desk, and a clean network setup is where that starts.

The honest bottom line

Don’t buy a leased line for the number on the brochure, and don’t cling to cheap broadband if downtime is quietly costing you orders and staff hours. Match the connection to how much you depend on it: full-fibre for most, a leased line where uptime and upload speed genuinely matter, and a backup line so a single fault can’t stop the business.

If you’re not sure which side of that line you fall on, we’re happy to look at how your team actually works — how many of you there are, what lives in the cloud, and where things slow down — and give you a straight recommendation. It’s part of how managed IT support is meant to work: the right infrastructure for your business, explained without the sales pitch.