I use an Arris TM602G cable modem with a DLink DIR-300 wireless router. After a few hours I cannot connect to any sites. I had the 'Enable DNS Relay' option set under the Lan Setup menu. Today, I have disabled this option and am connecting for the last 5 hours or so. I am not familiar with the menu options for your router, but if it has an Enable DNS Relay option then try and disable it.
Hopes this continue to work for me, and hope it works for you.
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