A. Determine what model of remote control you have according to the Remote Control Type Check.
B. Check remote control batteries according to type: MK1, MK2, MK3 Battery Level Check or MK4
Battery Level Check.
C. Check if the remote is assigned to the right room - this problem may occur if the TV in the other room is from a different manufacturer.
D. Check if the remote dongle is properly connected.
E. Pair the remote control.
If the issue is still not resolved: Replace with a new remote (together with a new dongle).