When you say it is overheating, how hot does it get, and how did you measure that? I would expect overheating components (CPU/GPU/RAM/SSD) to shut down completely, which is different than what many would describe as a “freeze”. What many would describe as a “freeze”, is more in line with a lacking network connection.
The 4K unit has an internal fan and thermal vents at the bottom. The heat dissipation works best when it is sitting on a smooth flat surface, and not e.g. closed in a small cabinet on three sides.
If the fan really isn’t rotating anymore (or not enough), then you should take it in for service. Dust is just an enemy of fans in here, as in any computer. The fan is close to silent (I’ve never heard mine), and likely with adaptable speed, and that will make it difficult to assess its workings. Any mechanical piece can break, but I wouldn’t expect a fan to give out only 8 months after its introduction; it is better engineered than that.