I've read your last post and understand clearly. I'd leave UPnP utility aside as you recommend.
The most highly related feature I found in my router I would say is ' Virtual Server'. The router help manual explains that it used to be set up for internal servers being accessed by the rest of the network beyond the router. My question is that can I suppose my aMule is a kind of internal server planted in my system? And what kind of internal server is it? For setting purpose, server type is needed to be selected, including DNS, FTP, HTTP etc.
Thank you for your help.