Senior Network & Infrastructure Engineer - L3 Engineer

About us
With 20 years in operation, SmartOSC is an industry-leading digital transformation agency of 1,000+ experts across Vietnam, Australia, Singapore, Japan, Thailand, Indonesia, Korea, the US, and the UK. Deep experience across most enterprise platforms and technology stacks has made SmartOSC a trusted partner for leading brands and financial institutions worldwide.With a "people-centric" strategy, we always strive to enable employees to grow sustainably and pursue their passion with a transparent career path.
For further information about SmartOSC, please visit [protected info]
Working Place:
Handico tower, Pham Hung, Tu Liem, Hanoi
Role Overview
We are looking for a Senior L3 Engineer to join our technical support and managed services team, taking ownership of complex technical escalations and critical incidents across network, cloud, identity, and security environments.You will act as the senior technical escalation point for issues that cannot be resolved at L1/L2, working closely with internal teams, clients, and technology vendors to diagnose problems, drive resolution, and prevent recurrence.This role requires strong hands-on technical expertise, structured troubleshooting skills, and the ability to communicate clearly with Australian clients during high-impact incidents.
Key Deliverables & Responsibilities
Technical Escalation & Incident Ownership
Take full ownership of complex and escalated incidents from L1/L2 through to resolution
Diagnose and resolve issues across network, cloud, identity, and security layers
Apply configuration fixes and changes on network and security devices (switches, routers, firewalls, wireless)
Lead root cause analysis (RCA) for major and recurring incidents, and document findings and preventive actions
Manage vendor escalations (e.g. Cisco Meraki, Sophos, Fortinet, Telstra, Microsoft), tracking cases through to closure
Communicate directly with clients during critical incidents, providing clear technical updates and resolution plans
Transfer knowledge to L1/L2 through runbooks, knowledge base articles, and coaching
Requirements
Senior-level experience in network, cloud, and security within a tiered or managed IT support environment
Hands-on experience with ITSM tools (ticketing, SLA tracking, incident management)
Strong knowledge of network fundamentals (routing, switching, VLANs, VPN, firewall policies, Wi-Fi)
Hands-on experience with Cisco Meraki, Sophos, and Fortinet platforms and their switch/router/firewall product lines, plus working knowledge of Telstra network services
Strong expertise in Microsoft Azure (networking, identity, security), including Microsoft 365 and EntraID
Proficiency in log analysis and structured problem-solving
Strong English communication skills, comfortable working directly with Australian clients
Required
Certifications:Network: Cisco CCNA or CCNP
Microsoft Azure: Azure Administrator / Security Engineer
Nice to have:
Experience with AWS and/or Telstra cloud services
Relevant certifications (e.g. Fortinet certifications: Fortinet NSE)
Sophos certifications, including Sophos Certified Engineer
Benefits
At SmartOSC, we offer the best to your values:
Attractive salary package
Salary review twice a year
Flexible working hours (between 7:30am - 7:30pm on staff's preference)
Premium health care
Working in one of the largest digital transformation agencies in Asia - Professional English environment
Firm's Certified Qualifications Sponsorship for career development
Annual company trip inside or outside Vietnam
Other fun activities: happy hour, quarterly team building, football club, yoga club, swimming club, charity activities, etc.
Free entertainment parties: Birthday party, Anniversary party, Sum-up Party, Year-End Party, etc
To Apply
Please submit your CV to [protected info] with the following information:Job application letter with "L3 Engineer" in the subject line.
Updated CV in English, including your contact email and phone number.
Personal Data Consent Notice
By submitting your resume for this position, you acknowledge and consent that the Company may collect, use, store, disclose (where necessary), and otherwise process your personal data for recruitment-related purposes, including evaluating your application, communicating with you, and making hiring decisions. Your personal data may be shared with relevant third parties involved in the recruitment process on a need-to-know basis. You acknowledge and consent that the Company shall retain your personal data for as long as necessary to fulfil the above purposes or to comply with applicable legal obligations.
Where permitted by applicable law, you may submit a written request for the deletion of your personal data.