[jabulon]

Most Bittorrent clients usually associate the TCP port number 6881. However, if this port is busy for some reason, the client will instead try successively higher ports (6882, 6883, and so on up to a limit of 6999). Most problems with being firewalled are due to the use of a router.

Most newer routers often have the option of UPnP or NAT-PMP built in. This allows for automatic forwarding of ports. Many clients use a randomized port at startup by default. This means that your port number keeps changing every time and that your router may block this port (incoming connections) (being firewalled).

The best way to avoid this, is to uncheck the options of UPnP, NAT-PMP and randomizing port number from the client you are using. Then fill in a port number above 10000. Now you have to open this port numer in your router and address that port number to the client you are using. Go to canyouseeme.org filling in the port number and test your connection.

For most clients the best ports to use are 49152-65534