If you sell an 'IoT product' to someone, and it doesn't work properly because of a wifi issue, then they will take it back to you and say 'the wifi don't work g

If you sell an 'IoT product' to someone, and it doesn't work properly because of a wifi issue, then they will take it back to you and say 'the wifi don't work good'. Then it's your responsibility to either refund them or replace it. That's how the law works. Now you have a defective Raspberry Pi, the wifi chip in it doesn't work. So what do you do? You do the same thing: you take it back to the person/company you bought it from and demand a refund, a repair or a replacement depending on whether it's a systemic issue with the chip or a one-off or whatever. If Raspberry Pi then end up taking up issue with Broadcom and complaining to them, that's their problem not yours, just as it's not your customers' responsibility to know only where they got the device. Whose fault is it? It's probably nobody's fault. But there's still a clear chain of responsibility.