Security Series Part 5: Network Security - Best Practices Every Organisation Should Follow in 2026

*Updated 7 October 2026*

Network security has changed considerably over the last few years, largely because the network itself has become more complicated.

For many organisations, the days of protecting a single office environment with a clearly defined perimeter are long gone. Users may be working across several locations, applications can sit across cloud and on-premise environments, branch offices need reliable connectivity and more devices than ever are connecting through wired and wireless networks.

All of this creates more flexibility for the business, but it also creates more areas that need to be understood and controlled.

43% of UK businesses identified a cyber security breach or attack in the previous 12 months, rising to 65% of medium-sized businesses and 69% of large businesses, according to the UK Government Cyber Security Breaches Survey 2025/2026.

The challenge for IT teams is therefore not simply keeping unwanted traffic out. It is making sure they understand how the network is being used, which systems are communicating with one another and whether the controls already in place still reflect the way the organisation operates today.

Network security is often strongest when it is treated as an ongoing part of network management rather than something reviewed only when new technology is introduced or a problem occurs.

What Does Good Network Security Look Like Today?

Good network security starts with having a clear understanding of the environment.

Organisations should know what is connected to the network, which devices and systems need to communicate and where access could be restricted without affecting day-to-day operations.

In practice, this can become difficult over time.

Networks rarely stay exactly as they were originally designed. New applications are introduced, offices expand, suppliers are given access, wireless networks grow and temporary changes are made to support projects or new services. Each individual change may be completely reasonable, but over several years the overall environment can become harder to manage.

This is why regular network reviews are so valuable.

They give IT teams an opportunity to look at the environment as a whole and ask whether the current design still makes sense. In many cases, the biggest improvements come from simplifying existing access rather than adding another layer of technology.

Why Is Network Segmentation Important?

Network segmentation is one of the most effective ways to reduce unnecessary exposure across a network.

Rather than allowing all devices and systems to communicate freely, segmentation separates different areas of the network and applies controls between them.

For example, guest Wi-Fi should not normally have access to internal business systems. IoT devices may only need to communicate with a small number of services. Critical servers may also need to be separated from general user traffic.

The value of segmentation is that it limits how far an issue can spread.

If a device is compromised on one part of the network, properly designed segmentation can make it significantly harder for that activity to move into other areas.

That does not mean organisations should divide their networks into dozens of highly restrictive zones without a clear reason. Over-segmentation can create unnecessary management overhead and make troubleshooting more difficult.

The better approach is to base segmentation on how the business actually works.

That means looking at which systems genuinely need to communicate, which users require access and where there is unnecessary connectivity that could be reduced.

Are Existing Firewall Rules Still Appropriate?

Firewalls remain a central part of network security, but their effectiveness depends just as much on the policies behind them as the technology itself.

Over time, firewall rule sets can become increasingly complex.

A supplier may be given access for a project. A new application may require an additional port to be opened. A temporary rule may be introduced during a migration and then never removed.

None of these decisions are unusual, but they can gradually lead to a situation where the firewall is permitting far more access than the organisation originally intended.

Regular firewall reviews should therefore look beyond whether the appliance is functioning correctly.

IT teams should also review whether the rules are still needed, whether they are too broad and whether temporary access has become permanent by accident.

Areas worth reviewing include:

• Rules that are no longer in use
• Broad source or destination access
• Duplicate or overlapping rules
• Temporary access that has not been removed
• Services that no longer need to be exposed
• Rules without a clear business owner

For many organisations, this kind of housekeeping can deliver a meaningful security improvement without requiring any major change to the underlying infrastructure.

Why Does Internal Network Traffic Matter?

External threats naturally receive a great deal of attention, but activity inside the network is just as important.

Once an attacker gains access to one device or system, the next step is often to look for other parts of the network that can be reached. This is known as lateral movement.

A flat network makes this much easier because devices and systems can often communicate with one another with very few restrictions.

Monitoring east-west traffic, which is the traffic moving between systems inside the network, can therefore provide valuable insight.

IT teams should have a reasonable understanding of which systems normally communicate and which traffic patterns would be unusual.

For example, a user device suddenly attempting to connect to multiple servers may be worth investigating, particularly if that behaviour would not normally occur.

This is where segmentation and monitoring work together.

Segmentation limits where traffic can go, while monitoring helps identify when unusual behaviour is taking place.

How Much Visibility Does The IT Team Have?

Visibility is one of the most important parts of network security because it is difficult to protect an environment that is not fully understood.

As networks become more distributed, it can become harder to maintain a complete picture of what is connected and how traffic is moving between locations and systems.

Useful network monitoring should help IT teams identify changes and behaviour that fall outside normal patterns.

This could include unexpected communication between systems, unusual increases in traffic, connections to suspicious destinations, new devices appearing on the network or repeated attempts to access restricted services.

The objective should not be to generate as many alerts as possible.

Too many alerts can quickly become noise.

The focus should instead be on creating enough visibility to help IT teams identify meaningful changes in behaviour and investigate them before they develop into something more serious.

How Should Wireless Networks Be Secured?

Wireless connectivity is now an essential part of most business networks, but it can introduce additional complexity if it is not designed as part of the wider security strategy.

Different categories of users and devices will often need different levels of access.

Employees may require access to business applications, while guests may only need internet connectivity. IoT or building management devices may only need to communicate with a small number of systems.

Separating these different groups can help prevent low-risk or unmanaged devices from gaining access to more sensitive parts of the network.

Wireless security should therefore be treated as part of the wider network design rather than as a separate project.

Centralised management can also help organisations apply consistent policies across several locations, which becomes particularly important where offices or sites have been added over time.

How Can Organisations Keep Branch Networks Secure?

Branch locations can easily become inconsistent with the rest of the network, particularly where different sites have been introduced at different times.

One office may have newer security infrastructure, while another may still rely on older equipment or a different configuration.

This can make the overall environment harder to manage and create weaker points in the network.

Organisations should aim to apply consistent policies across all locations, regardless of size.

Modern SD-WAN and network security platforms can help by allowing traffic, connectivity and security policies to be managed centrally.

This gives IT teams greater visibility across the organisation and makes it easier to apply the same standards to branch sites as the main office.

Consistency matters because an attacker is unlikely to care whether the weakest point is at headquarters or a much smaller branch location.

What Are The Most Common Network Security Weaknesses?

Many network security problems are not caused by a complete absence of security technology.

They are more often caused by environments becoming too open, too complicated or too difficult to monitor.

Common examples include flat networks with very little internal separation, overly broad firewall rules, unmanaged devices, poorly isolated guest networks and inconsistent security controls across different locations.

Legacy infrastructure can also create problems.

Older switches, wireless equipment and firewalls may continue to function perfectly well from an operational point of view, but they may lack the visibility, performance or management capabilities needed for a more modern environment.

Another common issue is poor documentation.

If the organisation does not have an up-to-date understanding of how the network is connected, it becomes much harder to assess whether existing access is still appropriate.

A Practical Approach To Reviewing Network Security

A network security review does not need to begin with a major technology replacement.

In many cases, the most useful first step is simply understanding the current environment properly.

A practical review can be structured around five areas.

Map The Environment

Build a clear picture of the network, including locations, devices, connections, applications and key traffic flows.

This provides the foundation for every other decision.

Review Connectivity

Look at which systems and devices are communicating with one another and identify connections that no longer serve a clear purpose.

Strengthen Segmentation

Separate areas of the network where appropriate, particularly where critical systems, guest access, IoT devices or operational technology are involved.

Improve Visibility

Make sure the IT team can identify unusual traffic patterns and unexpected changes across the network.

Review Regularly

Networks change constantly, so security controls need to be reviewed as part of normal operations rather than only during major projects.

This approach helps organisations improve security gradually while protecting existing investment and avoiding unnecessary disruption.

Network Security Checklist For 2026

The following questions can help organisations assess whether their current network still reflects the way the business operates.

1. Is there an up-to-date network diagram?
2. Does the organisation know what devices are connected?
3. Are critical systems separated from general user networks?
4. Is guest Wi-Fi isolated from internal services?
5. Are IoT and unmanaged devices appropriately segmented?
6. Are firewall policies reviewed regularly?
7. Are temporary firewall rules removed when they are no longer needed?
8. Is internal network traffic visible?
9. Can unusual network activity be identified?
10. Are branch locations subject to consistent security policies?
11. Are wireless networks centrally managed?
12. Are older network devices still supported?
13. Are network configuration changes documented?
14. Are third-party connections restricted to the systems they actually need?

If several of these questions are difficult to answer, it is usually a sign that the network would benefit from a more detailed review.

Where Should Organisations Start?

The most useful starting point is usually visibility.

Before making changes, organisations need to understand how their network currently operates, what is connected and where traffic is moving.

From there, it becomes much easier to identify where access can be reduced, where segmentation could be improved and where additional monitoring may be required.

Network security works best when it is reviewed continuously rather than treated as a one-off project.

The network will keep changing as the organisation changes, so the controls around it need to change as well.

How Can Britannic Help?

Britannic helps organisations review and strengthen network environments across LAN, Wi-Fi, firewall, SD-WAN and wider connectivity infrastructure.

The company takes an outcome-led approach, starting with how the existing network operates and where unnecessary risk, complexity or lack of visibility may exist.

This can include:

• Network architecture reviews

• Firewall and policy reviews

• Network segmentation

• Secure wired and wireless networking

• SD-WAN

• Branch networking

• Network monitoring

• Ongoing managed services

Britannic works with technology partners including Fortinet to help organisations improve security without introducing unnecessary complexity or replacing existing infrastructure where it is still fit for purpose.

Review Your Network Security

Speak to Britannic Technologies about reviewing your existing network architecture, identifying areas of unnecessary exposure and building a practical roadmap for improvement.