I’ve done all my testing with a
MiniPCIe to M.2 A+E key adapter.
FWIW, this NIC does work for me in both a HP T730 thin client as well as a HP MP9 G2 when connected to the A+E key M.2 slot that normally accepts a WiFi card.
It’s the Dell Wyse 5070 that unceremoniously doesn’t recognize the NIC.
I’ve tinkered around with various BIOS settings (short of attempting a BIOS extraction/whitelist edit/reflash), and the machine thinks nothing is connected to the M.2 slot (either in the BIOS or when booted to an OS). I thought the M.2 slot on that board/chipset might be CNVi-only (which might explain why WiFi works but not this NIC); however, I did find a M.2 A+E key Realtek NIC that is recognized just fine.
All this leads me to believe that some BIOS blacklist is blocking the i350 NIC, even once booted into Linux, despite never receiving a message / error on POST nor in the BIOS logs (which otherwise track chassis intrusion, missing keyboard/mouse, etc.).