OpenVPN Turris Shield

Maybe I’m acting a little stupid.
My shield is between my ISP modem and my home network.
ISP ( <=> WAN ( Shield ( LAN <=> Home network (

So far so good.
If I activate OpenVPN, I cannot connect.
My ISP modem has port forwarding (1194) to
And I have set up a static route (ipv4) from to

Maybe someone has an idea or the same problem. Without Shield I already had OpenVPN running on a Raspberry and it worked very well.