You can't use iptables command without root access. When logged as root, run iptables -L and check your firewall settings. FC1-3 have firewall enabled by default, so you WILL get LowID unless you either disable it or configure properly.
This of course have nothing to do with right router configuration. But if you can get HighID from another computer thru same router, that router must be fine. You using same port on BOTH linux and windows, don't you ? You don't want to confuse router
