Report Why is line of sight required with my Harmony 900? in General Questions Posted August 10, 2016 Weird things happening... It doesn't seem as if my IR blasters are working at all. I just eliminated my HTPC and built a NAS and added the Shield. This allowed me to eliminate a lot of wiring and also moved a bunch of stuff around. For whatever reason my AV receiver which definitely uses an IR remote works off the harmony with the blasters unplugged. The Denon remote that came with it will not work without line of site. My Playstation is no longer responding to the Harmony. Nothing else requires the blasters. No idea why they are not working all of a sudden... The Flirc is working with line of site but not with the IR blasters... I can understand if one stopped working but I have multiple ones mounted and I seriously doubt they all went bad at the same time. Gonna have to look into this more.