Basically, if I understand right the model uses 16.7 GB (gigabyte? gibibyte?), and it all has to fit into your VRAM + RAM. The backend uses an algorithm that's not transparent to me to fit a certain amount of that into your VRAM. 6 + 16 GB = 22 GB - the OS and other software using a certain amount - your laptop's iGPU using a certain amount, is making it a really tight fit, if it's even possible.