@MR.S 

But does that make sense? 

That's what WLAN groups are for. The best solution would of course be if you could select several WLAN groups per AP.

How could I realise this so that one WLAN is on all APs but each hall (in my case) still has its own WLAN with its own VLAN?

  @TW_EPC 

Hard to say since I don't know anything about your solution, but why use a separate VLAN for each hall? It just becomes a mess anyway when you roam between VLANs you get problems with IP addresses, when you roam between two networks with the same SSID the IP won't renew.

  @MR. S 

Well.

Actually, that makes sense.

The guest WLAN with the same VLAN in every hall should be available everywhere. However, each hall should also have its own productive WLAN with own vlan.

And I can only do that via WLAN groups at the moment. Because it makes no sense for me to broadcast ‘WLAN Hall 2’ in Hall 5 because it doesn't belong there. But the guest WLAN should already be there.

BR