a few people also reported similar problem.
i belive what we suspect is that some routers that have NAT mess around w/ ftp packets and change PORT commands on the fly. this screws up FXP transfers making it go thru your connection.
to confirm this, if you can, install bandwidth monitor and see if your bandwidth is in use. also, if you can, contact siteop and ask them to check where data is being sent while you fxp..to your ip or other site. try
www.dslreports.com zyxel forums. maybe they'll know how to (properly) configure your router.
or it could be coincidende indeed
