I had the same problem with my optiplex 3080 sff in which I tried to get a asus wifi6 card based on intel ax200 chip to work, this is what I did to get it to work;   1 disable aspm (active state power management) in Your computers cmos-setup (bios-setup) 2 disable aspm in windows energy settings, --> control panel - energy settings - change settings - change advanced settings - pci express - energy settings for link status - disable this setting (off)   This did the trick for my computer, after changing this setting my asus ax200 works like a charm and is  stable as a ordinary ethernet cabel.   Good luck.
There is a problem getting Windows 10 or Linux to recognize a DLINK X3000 PCIe WiFi card. This is a single lane PCIe card with an Intel AX200 card on it. I have tried slots 1, 2 and 3. The Bios correctly reports seeing a Network Card in any of the 3 backplane slots it is plugged into. However, Windows does not see the card when in slots 1 and 2. When inserted into slot 3, the 16 bit slot, Windows device manager sees that card. However it reports an error code 10 that it cannot start the card. I updated the Bios from 2.3.1 to 2.8.1 and it made no difference. I have also tried Linux Ubuntu 20.04.2 as the OS. lspcie only shows the card when installed in slot 3. Similar to Windows, Linux cannot successfully start the card. DMESG shows the driver is unable to load the firmware.  When the DLINK X3000 is installed in an Optiplex 9020, Windows 10 successfully starts the card and it operates as expected. I disassembled the DLINK X3000 and removed the Intel AX200 M.2 WiFi card from it. I installed the AX200 in the M.2 WLAN socket on the OptiPlex 3080 motherboard. Windows 10 sees the AX200 card and can start the driver. This sounds like a BIOS issue. I need to be able to plug the card into the backplane. Any suggestions how to fix this?
Optiplex 3080 Tower AX200 PCIe WiFi problem