DIAGNOSIS Yeah, this one's common. It's normal for it to get warm, even noticeably hot, during heavy use. The internal chips generate heat, and the casing acts as a heatsink.
FIX The main fix is ensuring it has room to breathe. Don't stack anything on top of it or put it in an enclosed cabinet. Stand it upright if it's lying flat—the feet on the side give better vertical airflow. Keep it away from direct sunlight or heat vents.
IF THAT DIDN'T WORK If it's so hot you can't comfortably keep your hand on it, or if performance drops (like the signal issue above), it might be defective. Check if it's under warranty. Excessive heat can shorten the lifespan.
HEADS UP Don't put it on a soft surface like a carpet or bed. The vents are on the sides and bottom, and blocking them forces the fan (if it has one) to work harder and actually makes it hotter.