Senior Infrastructure & Network Engineer

Role overview You will own the most complex infrastructure and network issues across on-premises, AWS, Azure and hybrid environments, acting as the final technical escalation point before vendors. Alongside operational ownership, you will play a lead engineering role in a multi-year cyber security uplift programme: rolling out Zscaler SASE (ZIA, ZPA), retiring Always-On VPN, and bringing customer remote access services in line with Zero Trust controls. Key responsibilities Senior escalation and technical leadership Act as the Level 3 escalation point for Level 1 and Level 2 teams, owning critical incidents, major problems and complex service requests through to resolution. Lead technical bridges during major incidents, coordinating engineers, vendors and stakeholders and communicating impact clearly to management. Mentor Level 2 engineers, review their fixes and build team capability through documented troubleshooting approaches. Set technical standards for network, server and cloud configuration, and review changes raised by other engineers.

SASE / SSE and Zero Trust (programme duties) Engineer and operate the Zscaler platform: ZIA for internet and SaaS security, ZPA for private application access. Deploy and maintain ZPA App Connectors in AWS, including integration with AWS Transit Gateway to reach customer jump service environments. Lead phased migration of users from Always-On VPN to ZPA, including pilot groups, parallel running, rollback planning and final decommissioning of RRAS infrastructure. Integrate Zscaler with Microsoft Entra ID for authentication, user group policy and conditional access. Configure ZIA policy for URL filtering, SSL inspection, DLP enforcement and AI application controls, working with Security Operations on tuning and exceptions. Deploy and support Zscaler Zero Trust Branch and SD-WAN appliances at office sites. Work directly with Zscaler Professional Services and implementation partners during deployment, then take ownership of the platform as business-as-usual. Produce design documents, runbooks and knowledge transfer material so Level 1 and Level 2 teams can support the platform after go-live. Administer and troubleshoot AWS and Microsoft Azure: VPCs and VNets, Transit Gateway, routing, security groups, compute, identity and service availability. Support Windows Server and Linux estates, including Active Directory, patching, hardening and performance diagnosis. Support virtualisation, storage and backup platforms, and lead upgrades and patching through change control. Cloud and server infrastructure Problem management and improvement Lead root-cause analysis for major and repeat incidents, and track remediation actions to closure. Improve monitoring and alerting coverage across network, SASE and cloud layers. Automate repetitive tasks with PowerShell, Python or Bash, and use infrastructure-as-code where it reduces configuration drift. Apply security, compliance and change management processes across all environments. Support vulnerability remediation, Cloud Security Posture Management findings, audits and ISO 27001 evidence gathering. Escalate risks and service-impacting issues promptly to the Programme Director, Security Lead and management. Security, risk and compliance Role and Responsibility We are looking for 8+ years in infrastructure , networking or cloud roles within complex IT environments, including at least 3 years at senior or Level 3 escalation level. Hands-on SASE or SSE deployment and operational experience; Zscaler (ZIA, ZPA) strongly preferred, with Netskope, Palo Alto Prisma Access or Cloudflare One also considered. Hands-on configuration and troubleshooting experience with at least two of: Juniper (Junos), Fortinet FortiGate, Palo Alto Networks (PAN-OS). Strong networking knowledge: TCP/IP, DNS, DHCP, BGP, OSPF, switching, firewalls, IPsec and SSL VPN. Hands-on administration of both AWS and Microsoft Azure, including cloud networking (Transit Gateway, VNet peering, hybrid c