The question is rarely "is ZTNA better than VPN" — it is "which access should move, and when." A remote-access VPN places a device on the network and trusts it broadly. Zero Trust Network Access brokers a user to a specific application, per session, after checking identity and device posture, and never exposes the underlying network. Understanding that difference is what makes the migration decision clear.
What actually changes
With VPN, once a tunnel is up the client can typically reach far more than the one application it needed — lateral movement is implicit. With ZTNA, the connection is application-scoped and outbound-initiated, so internal services are not exposed to the internet and an authenticated user cannot pivot to systems they were never authorised to reach. Posture and identity are evaluated continuously, not just at logon.
Sequence the migration by risk and friction
Start where VPN hurts most. Third-party contractors, vendors and BYOD/unmanaged devices are the highest-risk VPN population and the clearest ZTNA win — you replace broad network access with tightly scoped application access and far better logging. Named internal web and TCP applications are usually the next wave. Leave until later the workflows that genuinely need broad or low-level network access (some admin tooling, legacy thick clients, certain voice/UC paths); force-fitting these early creates frustration and erodes support for the programme.
Run both in parallel
The migrations that stall are the ones attempted as a hard cutover. Deploy ZTNA alongside the existing VPN, move one application or one user cohort at a time, and keep VPN as the fallback until each cohort is proven. Measure success per wave — connection success rate, help-desk tickets, and any application that needs policy tuning — before expanding. Decommission VPN capacity only once a cohort has run cleanly on ZTNA for a defined bake-in period.
Common pitfalls
Watch for applications that hard-code internal IPs or use dynamic ports, split-DNS assumptions that break when the network is no longer "flat," and device-posture policies set so strict on day one that legitimate users are blocked. Each is manageable when discovered during a phased wave and painful when discovered during a big-bang switch.