Thanks for your inputs mate .. I already tried the lan wire method and reset settings and restoring firmware too .. nothing solves the issue.
someone with same issue finally solved his issue with usb firmware flashing .. which he got it from denon website after pinging them for unlimited times ..
for now I am trying to do the same .. I am 100% sure this will be my last Denon purchase .. and I wont suggest denon to anyone ..
I really Don't want anyone to get into trouble like me