Not that I don’t believe you, but how are you sure that a kernel update is what fixed the Wi-Fi issue? Can you tell me how you came to that conclusion?
Also, have you tested the boot drive on the other laptop? It’s very likely that it has a different Wi-Fi device and therefore uses a different driver in the kernel. Let me know and I’ll help you as much as I can 🙂
paccache -r
got me about the same