@Nadar:
We're discussing the exact same issue in this thread: http://forum.pfsense.org/index.php?topic=65230.new;topicseen#new
From what I can understand, the reason is that the reply-to address for some reason isn't used for the return packets for the associated firewall rule for the port forwarding NAT rule. I've managed to get it to work by:
On the NAT port forwarding rule, select "none" under "Filter rule association". Create the rule manually instead, under floating rules. The rule is basicly a "copy" of the one automaticly created by NAT:
Pass, Quick, in, IPv4, <protocol>, source: any, Destination: port forwarding destination host, Destination port range: forwarded port
Make sure it's high up/on top in the floating rules, and make sure it's a quick rule. When I look in rules.debug, the effect of this is simply that the rule (it's the firewall rule that contains the reply-to address) ends up much higher in the resulting ruleset, and that seems to make all the difference. I haven't quite figured out why yet.</protocol>
Thanks! You saved me from a lot of troubleshooting. Is this a bug which has still not been fixed?