Hi Donald, there's not quite enough information, like what type clients, and only certain type clients?
Some certain type clients have an Apple pre-browser "Network Assistant" before they open Safari to get redirected for example?
You can bypass those type client CNA applications to help in some instances like you describe.
What vSZ firmware version and AP model? If this might have any relation to 5G radio, versus clients having established an initial
association, and then being able to roam between APs or AP bands?