The Johan
Sorry, for the group settings it's not possible to choose that. However if you are experiencing NAT behavior now on your groups, and you want the traffic for the subnet to be routed instead, you can use the routed subnets override found in the Advanced VPN page. If you specify for example 192.168.70.0/24 to be accessible for group "a" and you want that traffic to be routed, add that subnet to the routed subnets section in Advanced VPN as well to make it routed.