How to Plan Network Infrastructure for a Growing Business

Your network infrastructure is the foundation upon which every other technology decision rests. Email, file sharing, cloud applications, VoIP phone systems, security cameras, printers, point-of-sale systems — every single one depends on a reliable, well-designed network. For a growing UK business, getting the network right is not just a technical consideration; it is a strategic one that directly impacts productivity, security, and the ability to scale.

Yet network planning is one of the most commonly neglected areas of IT for small and medium-sized businesses. Too often, the network grows organically: a consumer-grade router from the ISP, a cheap switch bought from Amazon, Wi-Fi access points added haphazardly as the team expands. The result is a fragile, poorly performing network that becomes increasingly difficult and expensive to fix as the business grows. This guide provides a structured approach to planning network infrastructure that will serve your business well today and scale comfortably as you grow.

Start with the Internet Connection

Every business network begins with its internet connection, and choosing the right one is critical. For a growing UK business, the three main options are standard business broadband (FTTP or FTTC), a dedicated leased line, or a combination of both for redundancy.

Standard business broadband — particularly full-fibre FTTP connections now widely available across UK cities — offers speeds of up to 900 Mbps download and is perfectly adequate for many small businesses. However, the upload speeds are typically much lower (around 100 Mbps), and the connection is contended, meaning you share bandwidth with other premises in your area. During peak times, performance can drop noticeably.

A leased line provides a dedicated, uncontended connection with symmetrical speeds — meaning upload and download are equal. This is essential for businesses that rely heavily on cloud services, video conferencing, or VoIP, where consistent upload bandwidth is critical. Leased line costs have fallen significantly in recent years, with 100 Mbps connections available from around £200 per month in many parts of the UK.

For businesses with 20 or more employees, or those heavily reliant on cloud services, a dual-WAN setup is strongly recommended. This involves having two separate internet connections — typically a leased line as the primary and a business broadband or 4G/5G connection as backup. A properly configured firewall can automatically fail over to the backup connection if the primary fails, ensuring your business stays online. The cost of a backup connection is trivial compared to the cost of a complete internet outage.

Choosing the Right Firewall

The firewall is the gateway between your internal network and the internet. It is also your first line of defence against cyber threats. Consumer-grade routers — including the ones supplied free by ISPs — are completely inadequate for business use. They lack the processing power, security features, and management capabilities that a business network requires.

A business-grade firewall provides stateful packet inspection, intrusion detection and prevention (IDS/IPS), content filtering, VPN connectivity, traffic shaping, and detailed logging. For UK SMEs, the leading options include Cisco Meraki MX series, Fortinet FortiGate, SonicWall TZ series, and WatchGuard Firebox. Cloud-managed platforms like Meraki are particularly popular because they allow your IT provider to monitor and manage the firewall remotely without needing on-site access.

Structured Cabling: Get It Right First Time

Structured cabling is the physical backbone of your network. Whilst Wi-Fi is essential for mobile devices and flexible working, wired Ethernet connections remain the gold standard for desktop workstations, VoIP phones, printers, servers, and access points themselves. A wired connection provides consistent, full-speed connectivity with none of the interference, congestion, or latency issues that affect wireless.

When planning cabling for a new or refurbished office, install Cat6A cabling throughout. Cat6A supports speeds of up to 10 Gbps over distances of up to 100 metres, providing ample headroom for future needs. Cat5e, whilst still functional, only supports 1 Gbps and is a false economy given the minimal cost difference. Always install more cable runs than you think you need — adding cables after the walls are plastered and the carpet is laid is vastly more expensive than installing them during the initial fit-out.

Plan for at least two Ethernet points per desk position, plus additional points for printers, meeting rooms, and access point locations. Each cable run should terminate in a central patch panel in your comms cabinet or server room, where it connects to your network switches. Label everything clearly and maintain documentation — future you (or your IT provider) will be grateful.

Network Switches: The Heart of Your LAN

Network switches connect all your wired devices together and to the rest of the network. For a business network, managed switches are essential. Unlike unmanaged switches (which simply pass traffic between ports with no intelligence), managed switches support VLANs, Quality of Service (QoS), port security, SNMP monitoring, and remote management.

Power over Ethernet (PoE) switches are worth the modest additional cost. PoE delivers electrical power over the same Ethernet cable that carries data, eliminating the need for separate power supplies for devices like Wi-Fi access points, VoIP phones, and IP cameras. This simplifies installation, reduces cable clutter, and makes it easier to place access points in optimal locations without worrying about nearby power sockets.

Wireless Network Design

Wi-Fi is no longer a convenience — it is a critical business service. Employees expect to connect their laptops, tablets, and phones wirelessly. Meeting rooms need wireless connectivity for presentations and video conferencing. Visitors and clients expect guest Wi-Fi. Designing a wireless network that delivers reliable, secure, high-speed connectivity throughout your premises requires more than simply plugging in a few access points.

A professional wireless deployment begins with a site survey. This involves using specialist tools to map the radio frequency environment in your premises, identifying sources of interference, dead spots, and optimal access point placement. Factors such as wall materials (concrete and metal are particularly problematic), floor layout, ceiling height, and the expected number of concurrent devices all influence the design.

Enterprise-grade access points from manufacturers like Cisco Meraki, Aruba, or Ubiquiti UniFi provide far superior performance compared to consumer equipment. They support higher client densities, offer better roaming between access points, include dedicated management radios, and integrate with your network security policies. For a typical office of 500-1,000 square metres, expect to need three to six access points depending on the building construction and user density.

VLANs: Segmenting Your Network

Network segmentation using Virtual Local Area Networks (VLANs) is one of the most important steps in designing a secure business network. VLANs allow you to divide a single physical network into multiple logical networks, each isolated from the others. This provides both security and performance benefits.

A typical VLAN structure for a UK SME might include a corporate data VLAN for staff workstations and laptops, a voice VLAN for VoIP phones, a server VLAN for on-premises servers or network-attached storage, a guest VLAN for visitor Wi-Fi, and an IoT VLAN for printers, cameras, and smart devices. By segregating these networks, you prevent a compromised guest device from accessing your corporate network, ensure that VoIP traffic gets priority bandwidth, and limit the blast radius of any security incident.

VLAN	Purpose	Subnet Example	Internet Access
VLAN 10	Corporate data	192.168.10.0/24	Full (via firewall)
VLAN 20	Voice (VoIP)	192.168.20.0/24	SIP provider only
VLAN 30	Servers / NAS	192.168.30.0/24	Limited (updates only)
VLAN 40	Guest Wi-Fi	192.168.40.0/24	Internet only (isolated)
VLAN 50	IoT / printers	192.168.50.0/24	Limited (updates only)

Scaling for Growth

The most common mistake in network planning is designing for today's needs without considering tomorrow's growth. If your business is growing, your network needs to grow with it — and retrofitting a network is far more expensive and disruptive than building in capacity from the start.

When selecting switches, buy models with more ports than you currently need. A 48-port switch costs only marginally more than a 24-port switch but gives you room to double your connected devices. When planning cabling, install runs to areas you expect to use in the future, even if they are vacant today. When sizing your firewall, choose a model rated for the bandwidth and user count you expect in three to five years.

Consider your network monitoring and management strategy from the outset. Cloud-managed networking platforms such as Cisco Meraki provide a single dashboard for managing firewalls, switches, and access points across multiple sites. This makes it straightforward for your IT provider to monitor performance, identify issues, and make configuration changes without needing to visit each site. As your business opens additional offices or expands to new locations, the same platform scales seamlessly.

Security from the Ground Up

Network security should be designed into your infrastructure from the beginning, not bolted on as an afterthought. At the network level, this means implementing the controls required for Cyber Essentials certification — which is increasingly becoming a requirement for UK businesses, particularly those working with government or larger enterprises.

The five technical controls of Cyber Essentials map directly to network infrastructure decisions. Firewalls must be properly configured with default-deny rules. Secure configuration means changing default passwords on all network equipment and disabling unnecessary services. Access control means using 802.1X authentication on switch ports and WPA2-Enterprise on Wi-Fi. Malware protection means deploying network-level filtering and endpoint security. Patch management means keeping firmware up to date on all network devices.

Beyond Cyber Essentials, consider implementing DNS-level filtering (such as Cisco Umbrella or Cloudflare Gateway) to block access to known malicious domains before traffic even reaches your network. Network access control (NAC) can prevent unauthorised devices from connecting to your network. And comprehensive logging — with logs forwarded to a central SIEM or your managed IT provider's monitoring platform — ensures that security incidents can be detected and investigated promptly.