Thank you! Windows Firewall really blocked the ICMP packages. ??? How I made ithis beginners failure to not check this? :-[
Now everything what I need is working. There is still an Item I just can't understand. I can ping now from all clients all other clients in all locations, but my clients coming from outside over OpenVPN can't ping one of the Openvpn servers?!? Also the frontend of pfsense is not accessible from these notebooks if I choose the internal IPs. If I go over WAN, everything is fine?!?
Packet captures show, that the echo and the reply is visible in two devices only: The TAP of the server for remoteclients and the server for remoteclients itsself. Nothing in LAN or in the bridge interface…. It is really funny, that a ping goes over two VPN tunnels and two servers without any trouble, but the servers themselfes are stealh devices ;D