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What is the model of your Linksys router please?
What is the approximate distance between the Cable Modem & Router please?
OK, The Linksys Router is WRT320N.. It will be about 50 feet away from the Motorola SB 4630.
Hello there and thank you for your reply
Yes you can use your router as a Wi-FI "repeater", but you have to change the firmware that is inside the router to enable it to function as a "Repeater Bridge".
These webpages explain the methodology of what is involved and I can help you should you run into any problems:
Here are the instructions for your router.
If you are not comfortable with this procedure, then another option is to use Homeplugs (Ethernet Over Power) to connect the router to your Cable Modem.