The CM4 and Pi 4 use the Cypress CYW43455 for Wi-FI, which I found to be unreliable. Under load, it crashes, and it can't be fixed in the kernel.

Frustratingly, many other SoMs and SBCs use this chip. I don't understand why there is no recall on this - in my opinion - trash product. It's an odd feeling to be the only one experiencing this. I am 100% confident this is a design flaw in the CYW43455. I've seen this also on a Pine64 CM4 compatible SoM, which has a completely different SoC. This is on both the official and custom carrier. Cypress, fix your shit!

I believe that is actually a Broadcom chip, originally BCM43455.