A traditional VPN was designed on the assumption that most employees work from the office and occasionally connect remotely — a small, predictable slice of traffic. Hybrid work inverted that assumption without most companies redesigning the infrastructure to match, and the result is a VPN concentrator sized for occasional use now carrying most of the company's daily traffic, which is why it's slow and why it's become a single point of failure that didn't matter as much when it was lightly used.
The deeper problem with a traditional VPN in a hybrid-permanent world isn't performance, it's the trust model. Once connected, a VPN typically grants broad network access — the user is 'inside' the corporate network and can generally reach far more than their role actually requires. That made a certain amount of sense when VPN access was rare and mostly used by trusted staff for occasional need; it makes much less sense as the default daily connection method for the whole company.
Zero trust network access is the architecture that fits the current reality better — rather than granting broad network access once connected, each application or resource is authenticated and authorised individually, per request, regardless of whether the user is 'inside' or 'outside' any particular network boundary. This is a genuinely different security model from a VPN, not just a faster version of one, and it's worth understanding as such rather than buying a ZTNA product and configuring it to behave like the VPN it replaced.
Migrating from VPN to ZTNA is a real project rather than a quick swap, because it requires mapping which applications each role actually needs — the granular access model only works if someone has done the work of defining what granular actually means for each function. Organisations that skip this and grant broad access under a ZTNA label have kept the VPN's trust model with a different product name on it, and gained none of the actual security improvement.
