|Assuming the DSL-302G is already able to connect to the internet via a wired network adapter on the desktop computer connected directly to the modem's network port.... |
- the desktop computer should have no problem connecting to the internet when the network cable from the computer is connected to a network port other than the WAN one on the router, and the network cable from the modem is connected to the WAN port on the router.
I'm assuming, of course, that the led for each port on either end of the cable connection lights up when the cable is connected, when all devices are powered on and the computer is running, and that the "drivers" have been installed for the subject wired network adapter on the desktop.
On the other hand, using a USB cable connection between the desktop computer and the modem probably requires that you must install software for the modem, BEFORE you plug in the USB cable on both ends.
I'll see if I can dig up info about that for your modem.
The network cable between the desktop's wired adapter and the modem may need to be either a straight through wired or a cross wired cable due to the modem's requirements (usually that's the only thing you need the standalone modem's manual for to determine), but most modern routers will auto detect the type of cable and set something internally such that either type of cable can be used for any connection to the router.
If the clamp built into the end connector of the network cables that secures the cable's sheath does not have the cable's sheath under it, the wiring of the cable may have been damaged - there may be wires that are broken inside the individual wire's insulation - try another cable. The lever on the end connectors of the network cables should not be broken off and should no be "fatigued" - you should not be able to pull out the end connectors out of the network port unless that lever is depressed - the end connectors should "latch" in the ports. .
- for the wireless adapter on the laptop, if you haven't used the wireless feature of the router previously, wireless (broadcast) is often DISABLED by default - in that case, you must access the router's configuration by connecting to it via a network cable connection between the router and a wired network adapter on a computer, and ENABLE the wireless broadcast.
The default URL address you type in an internet browser program - 192.168.xxx.xxx, xxx being a specific number 0 to 255, inclusive - to get you to the router's logon screen, and the default user name and password you use at that screen to access the configuration settings, are in the manual for the Belkin router model - that's on the CD that came with the router.
(You're accessing the router internally, not the internet)
More info about setting up a wireless connection.
See response 3: