You can try any available legal port. Try one between 49152 - 65535 such as 64049.

The problem is probably either your software firewall or your modem/router but since you "refuse" to give us details, we really can't help you much more than what we have tried to. The forum rules specify you must detail your system & problem in detail as you agreed to the forum rules when you registered on the forum, & were shown a copy of the rules during that process which you agreed to. Forum Rules (click here)

But the problem might be your ISP. Since you haven't told us anything ... it's really anybody's guess. Sorry we don't have ESP! (Where's my crystal ball?!?!)