There's no need for clarification, you provided the link to the sticky post concerning illegal filesharing which was adequate, but I will still help with dcc connection problems all the same. The OP has been warned.~ Edit ~
As far as ports go, downloading is rarely blocked by your own ports.
And, for resuming, that's almost always on the sender's side due to a bad router setup using NAT.
Read up on the dcc resume protocol, when resuming it is the sender that connects to the receiver rather than the receiver connecting to the sender as with normal dcc.
...or maybe it's just passive dcc that works that way, although I was told by qwerty (or Merlin, can't recall which) when passive dcc was first added, that it was basically just using the resume protocol which puts the burden of open ports on the downloader instead of the sender as with normal dcc.