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 w