Computers behind OpenVPN Client cannot reach Clients behind Astaro

Good Afternoon guys,

since 7 days I am working on raspberrypi gateway solution in conjunction with the Astaro FW v9. The raspberryPi has the default ethernet NIC and has been equpied with a WIFI stick. RaspberyPi shall open a OpenVPN connection over internet to Astaro. Simple client server connection. The OpenVPN linkage shall be initiated over WIFI. The computer which will be hooked up with the default ethernet NIC shall be capable to reach all networks behind Astaro over Tun0.

Initializing OpenVPN(SSL):
RaspberryPi_Wlan0-->Internet->Astaro_includingOpenVPNServer

Stationary Usage:
Computer_Eth0-->Eth1_RaspberryPi_Tun0-->LocalNet1
-->LocalNet2
-->LocalNet3

What I did already accomplish

Computer is able to reach Eth1 by ping
Eth1 is able to reach all LocaNet's behind Tun0

What I didn't
The computer cannot reach the LocalNet's

In a different board I've been advised to adapt the SSL (OpenVPN)Server according to command-> push "redirect-gateway def1".
HOWTO

Hence, clients are supposed to be able to reach networks behind tun0

Since Astaro hasn't the diversity to make real customized configs from a webinterface point of view would it be viable to adapt this SSL (OpenVPN)config manually via SSH?

I appreciate every advice

regards