i dont understand how you could connect without using the NIC?
i say just use a network cable to connect from the nic to the modem, it should also have RJ45 jack to connect to.. and just dont use the usb for anything. (just power to the wall and conenction to the NIC)
in lspci do you see your NIC card information?
for the modem if you want to see the info, maybe you need to download the driver