Simultan openvpn client and server

I want to get running openvpn client and server at the same time. When the client is not active I can access the server but I don’t get a response when the openvpn client is running. Dyndns is working and recognizes the IP change, so ICMP is working. Maybe it’s a routing/firewall issue?! I tried this: (there is an Openvpn example) - without success. It would be nice if somebody could help me to find a solution.
Thanks in advance

Check/compare the routing with the vpn client up | down.