For instance, a B+M key SATA SSD will not work in some NVMe-only M-key sockets, and some proprietary standards like CNVi throw a wrench into the “any M.2 WiFi card will work with your laptop ...
2 M-key sockets specifically for that ... For PCIe, I recommend you use M-key for SSDs, B-key for WWAN-compatible cards and E-key for WiFi-compatible slots. These three slots can handle up ...