If the fault is occurring when your PS3 is in standby Brian it has to be a faulty PS3. The PS3 should not even be trying to connect to your router, wirelessly or otherwise, while it's in stand-by. I know you said you got a replacement but the may have fobbed you off with another return or have a faulty batch themselves.
Get on to sony and send it back, you have tried everything else!
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