all are ... :(

Router.... ???

if host paid will have router can give problem.

Not the router for the host, but the router attached to your own PC (either wired or wireless).

The router is the most common interface between a home computer and the internet service provider. By default, the router will close all ports and will only accept incomming traffic requested by apps on the clients machine. Unwelcome incomming traffic is bounced.

What this means, with regards to bittorrent clients, is that your own client can initiate a connection with other clients who's ports are open, but they cannot initiate a connection with you. If all clients are behind routers that block incomming connections, then no clients can communicate.

You need to chose a port (preferably in the range of 1000 - 65535) for your bittorrent client, then using the router software (traditionally accessed using a dedicated IP number), open the port you specified so that other clients can connect direct to your own client.