Outfire,
it probably doesn't help you much, but I just bought a 655 with 1.21 firmware and the wireless has been rock solid for me. My devices work everwhere in the house.
I've enabled the 'turn radio off' feature to turn off the RF between midnight and 6 am.
I don't know if that resets it daily and that is why it works, but it works - and very well!
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I attended a wireshark university session earlier this year where Laura Chappelle demonstrated some wireless captures using a special nic and software - she showed us lots of different interference patterns and if I remember she said uniden phone's were the worst offending phone devices she'd found - to the extend that she was confident she could disable a wireless user by taping the handset under the desk.
So rather than talk about the DIR-655, I'd have to ask if you have an alternate router that works (from the same location) If so, then at least you have that baseline. Beyond that, maybe you got a bad router - I'm sure it happens - wireless radio goes bad or something.