@GruensFroeschli:
Now that i think about it some more.
If you add another interface (and another subnet) and move the servers to this separate subnet (basically create a DMZ).
Shouldnt "true" NAT from LAN to OPT be possible?
–> Server loadbalancing should be possible again.
So what I'm gathering here is that the load balancing basically needs NAT to work? Is that correct?
Putting it on a separate subnet is not a bad idea; in fact for this particular application, it makes a lot of sense, since it's going to be "clients" connecting through a VPN. Even though I'm limiting what they can access, I have been mulling around the idea of separating the services they connect to to a completely different network (either with VLAN, or physically separate; it's a tiny network). If this would solve the load balancer issue it would be another reason to do this.