The number of people who connected all 6 zones in an event

I've developed an app for event. In the event there are 6 different zones and attendees can connect each other from each of the zone from the app.

My sample db table data is in below :

I am trying to get all the people who are connected in all the 6 zones.

I am struggling to write the mysql query for this.

Can you advise any approach with sample query code?

via Chebli Mohamed