VMWare vswitch portgroup VLAN to GS724T

Hi,

I'm struggling to have a GS724T switch 'untag' a VMWare vswitch portgroup tagged connection. VMWare states that the switch must be in 802.11Q vlan mode. I haven't found a specific settings for that, but here is my vlan and port setup:
Switch model GS724Tv3 boot B5.1.1.1 fw 5.0.2.22
The vswitch portgroup is assigned VLAN ID 25 and its interface is connected to port 24 on my Netgear switch.
The switch ports 13 to 20 are Untagged VID 25
The switch ports 21 to 24 are Tagged VID 25
Problem: (Untagged) Clients on port 13-20 cannot access the VMWare switch and infrastructure.

How do I correctly connect this switch using tagged VLANs to a tagged VMWare vswitch portgroup ?

Thanks a lot for help on this.

regards Tor