first of all i'd like to make sure you are aware of the secuity issues of
opening ports and letting third party applications run.

second of all i did the same but i redirected the ports 1 to 1 like

rdr ep0 207.207.83.53/0 port 7175 -> 192.168.1.2 port 7175 tcp
rdr ep0 207.207.83.53/0 port 51200 -> 192.168.1.2 port 51200 udp
rdr ep0 207.207.83.53/0 port 51201 -> 192.168.1.2 port 51201 udp
rdr ep0 207.207.83.53/0 port 51210 -> 192.168.1.2 port 51210 tcp

and it works perfectly well. sadly for one internal computer only but
that's a different story.

regards,
  shadi