news: today I called Dlink - they told me that DNS-323 and G624T (both dlink) are incompatibile ?
possible ?
It's not impossible, but I'd consider it unlikely. Both devices use time proven ethernet technologies and as long as they meet IEEE's 802.3 standards they should connect just fine - on the other hand, if either has a defect, or the cable connecting them is defective, or perhaps you disabled the auto-negotiation in one or the other, I could see you having problems.
Start by resetting them both to factory defaults and then test each one separately with known good devices to verify that they are both functional.