Im my own Hero,
i found the Problem, Zeroshell does start automatically the forwarding with static routes and so he override the settings from Netbalancer with this default setting. I disabled the forwarting in Network -> Routes and now on server side all VPN comes with every single IP Adress from my ISPs.
It was not the Problem of the Gateways. They are 192.168.1.1, 192.168.1.2, 192.168.1.3