Wifi client via OpenVPN and dhcp server

[ilconigliobianco]

Hi list,
  in my architecture, clients connect via wifi inside a tap openvpn tunnel to pfsense server.
  They have to receive an ip via dhcp and then they have to authenticate via radius to the network. To intercept the authentication I use the Captive Portal Server.
  I have created a bridge with two interfaces: openvpn and a lan interface where dhcp server listens ( private addressing )

I'm experiencing some problem, I can't receive the IP address ( my access point is connected to the vpn server ) and I can't configure the Captive Portal on an interface which is part of a bridge. Can you please give me some hints ????

Thank you very much