Hi &
to CF.
Some basics -
You can only plug one device into the modem at a time - ie router into ethernet port, PC into USB
OR ethernet.
If you change devices, eg unplug router and plug in PC, you should reboot your modem (leave off for 20sec)
The router will have an ethernet port label WAN separate from the other four ethernet ports. The cable from the modem plugs in here.
Your PC should plug in to one of the four remaining ports.
I would recommend -
1. Turn all three off.
2. Plug in both ethernet cables, as above.
3. Turn on modem.
4. When modem lights settle, turn on router.
5. Start up PC.
With any luck it should work straight away.
You may need to login to the 'belkin screen', which should be described in the manual.
HTH