Advanced double NAT VPN question

  • Hi,

    i have a IPSEC Site to Site VPN with NAT from the VPN Endpoint to my LAN Works fine!

    Then i have an Open VPN Server in TAP Mode. Network here is

    The goal is that Clients that connect to the OpenVPN VPN can reach the other Site of the IPSEC Tunnel. This will not work, because the IPSEC NAT awaits only Clients from net

    So i added a second NAT from Net to Address when Destination is the IPSEC Tunnel.
    This works too. A ICMP Ping is natted from Openvpn Net into my Lan. From my Lan natted into the IPSEC Endpoint net. Through the Tunnel. Then i get a Ping response BUT the way Back from to (my Lan) does not work. Why?
    What is the difference between a Ping from my LAN Network and a Ping from a natted IP in my LAN Network? Or do i have to setup any forwards?

    Thanks for any ideas.