L3 Network Engineer (CISCO) - Must have an active SC or DV Clearance - Must be willing to apply for DV if SC Cleared An opportunity is available for an experienced L3 Network Engineer (CISCO) to join a committed team supporting UK Military systems. This is a fully on-site role in Portsmouth and requires strong 3rd line network support expertise, particularly in secure environments. You will work on incident resolution and system change implementation across LAN and WAN networks. Key Responsibilities Provide 3rd line support for LAN and WAN environments Manage escalated incidents from 1st and 2nd line teams Implement approved changes to live systems Install, configure, maintain and troubleshoot routers, switches, firewalls and related cabling infrastructure Perform IOS and firmware upgrades on network devices Update and maintain network design documentation Offer network advice and input to design changes Support operations in multi-security tier and multi-tenant environments Mandatory Skills Strong experience in 3rd line network support Configuration and troubleshooting of CISCO devices ASA and Firepower firewall experience Familiarity with VMware NSX Firewall and SDWAN Understanding of NGNIX and Linux systems Experience in multi-tenant and high-security networks Desirable Skills Documentation of network changes and design updates Effective collaboration with cross-functional teams Experience supporting defence or military environments This role is suited to an experienced and security-cleared network engineer who enjoys hands-on support in high-assurance environments. To apply send your CV for review