10 Common Network Security Mistakes UK Businesses Make – And How to Fix Them

In today’s fast-moving digital world, network security is no longer just the concern of large enterprises or IT departments—it’s a critical issue for every UK business. Whether you’re a growing SME in Manchester or a multinational in London, the risks of a cyberattack are real and growing.

Despite increased awareness, many organisations still fall into avoidable security traps. Here are 10 of the most common network security mistakes UK businesses make—and how to steer clear of them.

1. Relying on Outdated Firewalls and Routers

Many UK businesses install a firewall once and forget about it. But cyber threats evolve fast—and yesterday’s defences won’t stop today’s attackers.

Fix: Regularly update or replace legacy hardware, and consider next-gen firewalls with deep packet inspection and application awareness.

2. Weak or Default Passwords Across Devices

Default login credentials or weak passwords on routers, servers, or endpoints are still shockingly common—especially in smaller firms.

Fix: Implement strong password policies and use multi-factor authentication (MFA) wherever possible.

3. Ignoring Software and Firmware Updates

Unpatched systems are one of the top attack vectors used by ransomware gangs and state-sponsored actors alike.

Fix: Set up automated patch management and track all critical updates, including firmware for networking hardware.

4. Poor Network Segmentation

Many UK businesses operate with flat networks—meaning once an attacker gains access, they can roam freely.

Fix: Implement network segmentation to isolate departments, devices, and sensitive data, reducing lateral movement in the event of a breach.

5. Lack of Employee Security Awareness Training

According to the UK’s Cyber Security Breaches Survey, phishing remains the top threat. Human error is often the weak link.

Fix: Run regular cybersecurity training, phishing simulations, and awareness campaigns—especially during high-risk periods.

6. Not Monitoring Network Traffic

Without proper monitoring, threats can lurk unnoticed for weeks or months.

Fix: Deploy a Security Information and Event Management (SIEM) solution, or partner with a UK-based Managed Detection & Response (MDR) provider.

7. Insecure Remote Access Setups

The rapid shift to hybrid work has left many businesses with poorly secured VPNs or exposed RDP ports.

Fix: Use encrypted VPNs, enforce MFA, and restrict access to essential personnel only. Consider zero trust network access (ZTNA).

8. Failing to Back Up Critical Data

Even today, too many businesses have either no backups or improperly configured backups—leaving them vulnerable to ransomware.

Fix: Follow the 3-2-1 rule: 3 copies of data, on 2 different types of media, with 1 offsite (or in the cloud). Test backups regularly.

9. Assuming Cybersecurity is Just an IT Problem

Network security should be a board-level priority—not just left to the tech team.

Fix: Embed cybersecurity into business strategy. Involve leadership in policy-making, risk assessments, and budget planning.

10. No Incident Response Plan in Place

When an attack happens, time is critical. Businesses without a response plan waste valuable minutes—and risk reputational damage.

Fix: Create a clear incident response plan, run tabletop exercises, and know when and how to notify the ICO and affected customers under UK GDPR.

Conclusion: Prevention is Cheaper Than Recovery

The cost of a network security breach isn’t just financial—it can affect customer trust, operations, and compliance. With the UK government investing heavily in cybersecurity awareness through initiatives like Cyber Essentials, there’s never been a better time to review your network security posture.

By addressing these 10 common mistakes, UK businesses can significantly strengthen their defences and stay ahead of emerging threats.