Do you see anything else in the packet filter log? Thinking about the line in your first post from the live log, I would have made a NAT rule:
{199.108.0.133} -> HTTP -> External (Address) : DNAT to {192.168.2.1}
select 'Auto packet filter rule'
But, the Astaro is a stateful firewall; it automatically should accept and route responses, so I'm curiuos why you would need a DNAT or even an inbound packet filter rule. Typically, a DNAT is needed only when you want to accept unrequested packets as when you offer a webserver. Unless SOE "pushes" things to you on its own schedule, there's another problem.
The full packet filter log has more information than the live log. Let's look at the same line above from there. Also, what instructions does SOE give about firewalls?
Cheers - Bob