i use a HDD all the time and never had a problem so i dont no where u got that from, and it doesnt matter if you can use the intenet channel games over NWFC need a constant connection to update player locations etc, as the net channel only uses as needed, try getting yourself a netgear or something.
thew only other thing i can think of is your getting booted for doin something u shouldnt be, but im sure thats not the case!