Hello

We can try to diagnose what is happening from photos you can upload to this site.  Please take photos of the entire shrubs and then, some close-ups of anything that may be occurring on the leaves, branches, etc.

Thank you for the photos. It looks like the boxwoods are battling boxwood leaf miner, which causes the sort of blistery-looking and brown leaves, as well as the boxwood psyllid. You can read more about these pests and management here: Boxwood insect pests

For the yews, those lines of holes look like damage from a bird - possibly a sapsucker. I don't think this feeding (or the amount I can see in the photos) would cause that much browning/die back in the canopy, though. The browning of the above ground growth is symptomatic of a few things - sensitivity to de-cing salts (is this plant near a sidewalk?), root issues (what is the soil like in this area - yews do best in well drained soil and are sensitive to "wet feet") and winter damage. Has there been any sort of construction or recent changes near the yews?