L3 Network Engineer / Senior Network & Security Engineer

Job Title: L3 Network Engineer / Senior Network & Security Engineer Location: Changi Business Park, Singapore Employment Type: 12-Month Renewable Contract Work Arrangement: On-site We are looking for a hands-on L3 Network Engineer / Senior Network & Security Engineer to manage, support and improve enterprise network infrastructure across HQ and retail environments. The ideal candidate must have strong hands-on experience in routing, switching, core/distribution/access network architecture, firewall, VPN, VLAN, network troubleshooting and network design. This role requires someone who can independently diagnose complex network issues, support network changes, work with vendors, and contribute to network improvement and design activities. Key Responsibilities Manage, maintain and troubleshoot enterprise network infrastructure, including routers, switches, firewalls, VPN, LAN, WAN and wireless networks. Provide L3 network support for complex incidents involving routing, switching, VLAN, trunking, STP, inter-VLAN routing, ACL, NAT, VPN and firewall connectivity. Support core, distribution and access switch environments, including configuration, troubleshooting, firmware upgrades, performance tuning and lifecycle management. Perform network design and improvement activities, including reviewing existing setup, proposing enhancements, preparing diagrams, and supporting network architecture improvements. Support routing protocols and network technologies such as static routing, OSPF, BGP, VRRP/HSRP, LACP, VLAN, STP, trunking and subnetting. Administer and troubleshoot firewall policies, NAT rules, VPN tunnels, access control, network segmentation and security configurations. Support network infrastructure rollout for new sites, retail stores, office changes, migrations, upgrades and refresh projects. Work closely with vendors, telcos and service providers for circuit provisioning, escalation, troubleshooting and service restoration. Perform root cause analysis for network incidents and recommend preventive actions to reduce recurring issues. Monitor network performance, availability and security alerts, and take proactive action to ensure stability and uptime. Maintain proper network documentation, including network diagrams, IP addressing, device inventory, configuration records, SOPs, change records and troubleshooting guides. Support security-related activities such as vulnerability remediation, patching, network hardening, audit support and firewall rule reviews. Provide on-site support at HQ and retail stores when required for incident resolution, deployment or infrastructure changes. Requirements Minimum 5 years of hands-on network engineering experience, preferably in enterprise, retail, financial services, healthcare, manufacturing, telco or multi-site environments. Strong L3 networking knowledge with hands-on experience in routing, switching, VLAN, subnetting, trunking, STP, ACL, NAT, VPN and firewall troubleshooting. Good understanding of core, distribution and access switch architecture. Hands-on experience with routers and switches from Cisco, Aruba, HPE, Fortinet, Juniper or equivalent. Experience supporting firewalls such as Fortinet FortiGate, Palo Alto, Cisco ASA, Sophos or equivalent. Able to troubleshoot complex network issues independently and clearly explain technical findings, root cause and resolution steps. Experience with network design, network diagrams, HLD/LLD, migration planning, change implementation and documentation. Experience working with vendors, telcos and service providers for escalation, delivery and issue resolution. Comfortable working on-site at Changi Business Park and travelling to retail stores when required. Strong ownership mindset, good communication skills and ability to work independently in a hands-on technical role. Preferred Skills CCNA or CCNP certification, or equivalent hands-on experience. Experience with Fortinet / FortiGate firewall and SD-WAN. Knowledge of Azure networking or cloud connectivity will be an advantage. Exposure to network security, vulnerability remediation, audit support or compliance requirements. Experience supporting multi-site retail environments will be advantageous. Ability to communicate in Mandarin will be an added advantage for stakeholder or vendor coordination. Ideal Candidate Profile The ideal candidate should be a strong hands-on network engineer who is confident in L3 troubleshooting, network design, routing, switching, firewall and VP…