Motorola DCX3200-M suddenly stopped responding to remotes at > 3-4 ft

Hi - I have a Motorola DCX3200-M provided by Cox that has been used for about five years. I still have cable service through Cox and nothing has changed in that regard. While watching TV today, out of nowhere the cable box stopped responding to any input from remote controls at further away than 3-4 feet. I have two TV remotes that typically work with this box - one provided by Cox and one that is a universal remote that came with my TV. The exact same problem started occurring with both remotes at the exact same time. I have attempted changing the batteries in the remotes. I have attempted to reprogram codes into the remotes to match the model of cable box I have. The remotes work fully and normally when within 3-4 feet of the cable box but not any further out now. I have attempted unplugging the cable box, waiting 10 minutes, and then plugging it back in. This did not fix the problem. There are no changes in lighting in the room. No new electronic devices of any type have been installed within 50 feet of the cable box. No work has been done on networks, power lines, or any other source of infrared or EMP transmissions nearby. The cable box has not suffered any physical trauma or changed locations. There have been no recent power surges or power loss here aside from when I unplugged the box for 10 minutes earlier tonight. Any ideas on what may be going on and anything I could try to do to fix it?