That sounds like something on your ISPs side. There is a chance they may be monitoring your activity and looking for gnutella connections and disconnecting you for this. Although that is strange I have seen other gnutella users with an road runner IP address, although I have not checked any time recently. You might want to try changing the port settings from 6346 to something else like maybe 1234, Im not sure what else can be done right now, you may have to specify yourself as behind a fire wall.