IFAIK MAC address filtering is only on the wireless side, may be wrong, (sorry I’ve lost track of how your Denon is connected) so if you have a hard connection then that might not be it. But if it is you should be able to just disable it in the router’s settings and see if that works.

3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1