they ask how our office wifi network is secured

Wifi security falls under access policy, not under a separate question

The question about wifi security is usually a concretization of a broader question: how does the enterprise manage access to its systems and business assets. A standalone answer about "WPA3" or "a separate guest network" is fine, but in the file it really belongs as part of access policy, including management of business assets. Network equipment — routers, access points, switches — is a business asset, and the way it is managed (password policy, firmware updates, segmentation of guests and employees) is precisely what that question tests.

You typically answer with three elements: the encryption protocol used (WPA2-Enterprise or WPA3), whether guests and employees are on separate networks, and who is responsible for managing the access points. If you have no formally documented wifi policy but do have a working practice — an IT supplier managing this, for example — you answer based on that practice and refer to it in the file. If both the policy and an identifiable practice are missing, then "no" or "partial" is the honest answer; a list with missing cyber data does not result in approval, not even tacitly.

Traceable to Annex A and Article 21 paragraph 2 NIS2

Under ISO/IEC 27001, network security falls under the control measures in Annex A, specifically under the category that governs access control and network segmentation; an auditor asking for evidence usually asks in practice for the wifi policy as an illustration of that broader measure. Under the NIS2 Directive, Article 21 paragraph 2, access control and network security fall under the ten measures listed there, without wifi being named as a separate point. If you yourself fall under the Directive or the Dutch Cybersecurity Act — that follows from whether the enterprise itself falls under the NIS2 Directive or its national transposition — then network security is one of the subjects you must be able to report on, even though the law does not use the word "wifi".