Shared Walls, Shared Bandwidth: What a Serviced Office Really Signs You Up For

The brochure is lovely. Exposed brick, a decent coffee machine, a meeting room you can book by the half hour, and — tucked away in the small print of the services schedule — "high-speed business internet included". For a five-person firm escaping a lease, that last line is often the clincher. No Openreach engineer, no six-week lead time, no line rental to argue about.

Then you move in, and discover that "included" and "under your control" are two very different words.

The connection isn't yours, and neither is the responsibility

In a serviced or managed office, the building runs a shared circuit — usually a leased line or a business FTTP package — and splits it across tenants. You get a port, a Wi-Fi SSID and a router you're politely asked not to touch. It generally works. It's generally fast enough. And on the day it doesn't work, you become a passenger.

Your IT support can't log a fault with the provider, because your firm isn't their customer. Your ticket goes to the building manager, who relays it to a facilities company, who relays it to the ISP. Each hop adds an hour and removes a detail. If the fault turns out to be a switch in a cupboard you don't have a key to, you're waiting on someone else's priorities.

That's not a reason to avoid serviced offices. It is a reason to find out exactly where the boundaries sit before you sign.

The static IP question nobody asks

Here's one that catches people out months later. Shared tenant connections very often sit behind carrier-grade NAT. Everyone in the building shares the provider's public address, and nobody gets a static one — or if they do, it's a paid add-on managed entirely by the landlord's supplier.

Why does that matter? Because anything you host or permit-list starts to wobble. Remote access to a small server. A VPN endpoint. A CCTV box the security firm wants to reach. A card payment terminal that a provider wants to whitelist. Even your Microsoft 365 tenant admin who's trying to lock down access by IP.

If a static IP is on your roadmap at any point in the next couple of years, ask now. "Can we get one, what does it cost, and who administers the change?" is a much easier conversation before the lease than three months in.

Someone else's reputation becomes your reputation

This is the part that stings, and it's the one small firms rarely see coming.

Shared outbound IPs mean shared sender reputation. If a tenant two floors down runs a poorly configured mail-merge from a compromised mailbox and gets the building's address listed on a major blocklist, your invoices can start bouncing. Not because you did anything wrong — because the postcode on your email envelope got tarred along with theirs.

If you're sending anything that matters through an on-premises mail server or a shared SMTP relay, that's a real exposure. The good news: it's also easily sidestepped. Route business mail through a reputable cloud service with its own sending infrastructure, keep SPF, DKIM and DMARC tidy on your own domain, and your deliverability stops depending on whoever shares your riser cupboard.

Do check which of your day-to-day tools actually use the building's connection. A surprising number of small firms discover their CRM's email notifications or their accounts package's invoice-sending service have been pointed at a local relay since setup.

The firewall you can't see

A shared connection typically comes with a shared edge device managed by the building. That's fine for basic web browsing, but it means:

• You can't set your own inbound rules.
• You may not be able to run site-to-site tunnels for a second office.
• Port blocking policy is whatever the building decided, which could break an odd but essential line-of-business app.
• Logs, if any exist, belong to someone else — awkward if you're ever asked to produce evidence for an insurer or a client's due diligence.

For most small firms, the sensible answer isn't to fight for control of the building's firewall. It's to stop depending on it. Put your own small router or firewall behind the provided port, keep your staff on your own Wi-Fi network with your own password, and treat the building's connection as an untrusted uplink — the same way you'd treat a hotel network.

Questions worth putting in writing to the building manager

Ask these before you sign, and get answers by email:

1. Who is the ISP, and what's the contracted speed and SLA?
2. Is the connection contended, and what's the ratio?
3. Can we obtain a static IP, and at what cost?
4. Are there restrictions on inbound ports or VPN traffic?
5. What's the escalation path for a fault, and what's the typical fix time?
6. Is there a secondary or diverse connection, and does it fail over automatically?
7. Can we install our own line or dish if we choose to?
8. Are there any other tenants in the building running public-facing servers?

Question seven matters more than it looks. If there's any route to bringing in your own circuit later — even a cheap FTTP line for redundancy — you keep an exit.

Making it supportable without buying your own fibre

You do not need a dedicated leased line to run a tidy five-person office. You need clarity.

A workable setup usually looks like this: the building's connection as the primary uplink, terminated into your own router so your LAN and Wi-Fi stay under your control; a 4G or 5G backup device that kicks in when the shared line drops, sized to keep email, Teams and your line-of-business app alive rather than everything; business email through a cloud provider with correct DNS authentication; and a documented note in your IT records saying exactly who to ring when the internet dies.

That last item is worth more than any of the others. Because the worst version of the serviced office trap isn't slow broadband. It's a Monday morning where nobody in the building knows whose problem it is.

Before you sign

Read the services schedule as carefully as the lease. Confirm in writing what's shared, what's dedicated, and where your responsibility ends. Then test it in the first week — run a speed check at 10am and 3pm, send a test email to an outside address, and try connecting to your VPN from home. Better to find the edges of the arrangement while you still have leverage.

Flexible office space is a good deal for a lot of small firms. It's just a better deal when you know which parts of the network are yours, and which parts are simply on loan.