[madrebel]

sounds like youre getting a loop.

imagine if you will

@ = external
$ = router
% = server
# = you

@----->$--forwards to---%

packet comes in for port 12203 hits the nat box gets routed to the server

whats happening is

#----->$----%---->$----->%---etc

you, send a packet to the server on port 12203, it first hits the router the router send its to the server....the server then sends back the info destined for the client on port 12203....that packet hits the router and gets forwarded back to the server(since all traffic on those ports gets forwarded to the server). So instead of it getting back to the client it just loops.

Thats what sounds like is happening anyways.

btw, before you go thinking youre secure with that router. youre not. a packet filtering firewall(what you have) is the least secure of all firewalls.

DMZ the server and put a software firewall on it. You will have the same level of security doing it that way.