Chances are no, they won't work. The amount of ferromagnetic material in an ethernet cable is minimal at best, so you won't get any magnetism between the cable and the magnet. Simply put - the cable won't stick.
If you can get a fish tape down from the upstairs duct you should be able to tape the cable to it and pull it back up. Failing that, take a deep breath and cut the drywall. Fixing a small hole is absolutely no big deal, even if you have ten thumbs.
-drin
Chances are no, they won't work. The amount of ferromagnetic material in an ethernet cable is minimal at best, so you won't get any magnetism between the cable and the magnet. Simply put - the cable won't stick.
If you can get a fish tape down from the upstairs duct you should be able to tape the cable to it and pull it back up. Failing that, take a deep breath and cut the drywall. Fixing a small hole is absolutely no big deal, even if you have ten thumbs.
-drin