[Smilie]

as Toto said
u connect the modem to the routers WAN socket with ethernet lan cable
then u connect your PC and/or other device to the 1-4 ports also with a ethernet lan cable
USB cable should not be used at all
then power down all the equipment
and turn them on 1by1 in order of
modem -> routher -> PC and other devices

and with the 1-4 number lights
only if the corresponding sockets are connected and used will they turn on