Unable to setup 4K UHD output
I have a Sony 4K UHD TV, new Denon 4K AV receiver and, just installed, new audioquest Forest 48 HDMI cables (rated for 8K - 10K), but the best output available, per the Xfinity box, is only 1080p. The Xfinity box is PX013ANM. Our service is X1. Any help in getting the box to output UHD would be greatly appreciated.