Which approach is recommended when user density exceeds the original WLAN design?

When user density exceeds the original WLAN design, conducting a thorough site survey and redesigning the network is the appropriate approach because it ensures that the network can adequately support the increased number of users. A site survey provides insights into the existing coverage, identifies areas of congestion, and helps determine the required adjustments to improve performance.

Redesigning the network based on the survey findings can involve increasing the number of access points, optimizing channel assignments, and adjusting power levels to enhance capacity and coverage. This proactive approach addresses not only the current demands but also future-proofing the network against potential further increases in user density.

The other options, while they may seem beneficial in certain scenarios, do not adequately address the need for a tailored response to increased user density. Adding more users to existing devices can lead to network congestion and degradation in performance. Incorporating higher-capacity switches, while it might enhance wired connectivity, does not directly resolve issues related to wireless access point capacity. Restricting the number of connected devices limits user access and doesn't solve the underlying problem of capacity and coverage that a redesign would address effectively.