I'll contact warranty support and see what they say. Thanks for your help anyway.
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I will consider DIR-655, if I have to buy a new router.
I have still superfast internet connection (40mbps) regardless of the issue. It just feels kinda stupid and inefficient not to take advantage of the full speed. Not that I'd actually need the extra speed...
I'll keep you posted about how D-link replies, unless I get tired of this altogether and rush to the store to buy a new router.