ok (sorry about my english again)
for example, the most common ports, 4662 and 4661 are filtered in some countries, because of legal problems with p2p or because of the problems with de bw of the ips.
note: in a filtered port, you can estabilish a conection, but the router sometimes discard packets, and you loose these conections because of timeout. and obviously you can't upload/download nothing, or only a bit.
it would be ok an option to add ports manually one time you start the program (for example in preferences), not to implement directly in the code (this is my case ;() with an "if" saying that conections with servers or clients thru these ports are rejected.
greetings