Worth adding: Your TV is a 1080p display. I would EXCLUDE any resolutions that are above 1920x1080 from your list. 2160p is flat out silly to send to your TV as your TV is 1920x1080 (1080p) resolution.
If you lower your resolution to the actual native rate of the Sharp display, do you continue to have any issues at all? Or do you still have issues? If you do have issues, even after fixing your resolution to 1920x1080 from the player, then the issue is almost certainly DHCP related, and most likely caused by your display.
It is extremely unlikely that it is your cable, but with 2160 resolution, it could introduce some cable issues. Typically this is shown by sparklies on the screen or no image at all. It would not be typical to show up as a sharp line on screen as you described.