Hi Syliva.
It is the D34010WYK and I have tried 2 wifi cards and both are as bad as each other. However, if I move the NUC to the same room as the wifi router I get 300Mbps connection on both 2.4 and 5 GHz, but when I move it back to the living room, 20ft away it drops terribly back to less than 100Mpbs at times.. where my HP laptop with the exact same wifi card in never skips a beat and it connected to the full 300Mpbs in the living room, next to the NUC.
I guess I am having to go back to a homeplug? as yes the antennas are connected correctly and I did try a different antenna, same issue.. is it the lack of power int eh NUC itself?
Cheers
Mark