I hadn't previously tried that, but it didn't help when I did try it.
It's been a crazy exchange of messaging with Dell technical support so far, with them saying my XPS 9520 with factory AX 211 doesn't support Wi-Fi 6E. Although I have the same problem with my AX210 in my Precision 7560 which is supported according to Dell has the exact same problem and addressed in my support request.
I wish I could screenshot a snap of all my PM exchanges to highlight the incompetence I'm dealing with. So far Dell's response is that the XPS 9520 with AX211 adapter does not support 6GHz. When I confronted them with the exact same issue I am having with my Precision 7560, which is validated by Dell, they seem to have opened up a little bit.
What you describe sounds like the Bios is Whitelisting what hardware is allowed:
A BIOS Whitelist is OEMs list of compatible hardware. They restrict their users from buying any other brand. This post explains BIOS Whitelist and how to remove it.
www.thewindowsclub.com
I have this issue with an older Sandy Bridge HP laptop, the teardown manual says it will accept 5 or 6 wifi cards yet only 1 model works,
I've tried them all. (only discovered this after buying an AC upgrade that would cause the unit not to post) It's N rated.
Dell needs to give you a Bios that lifts the restriction.
You can try a couple of things:
From Windows "All Settings" > "Network & Internet" you can try:
1) from Network settings scroll to bottom and try "Network reset" This should be the same as above
but letting Windows do its own thing. PLUS REBOOT (they've made so many changes that this could work slightly differently / unknown.)
***2) from "Device Manager" uninstall the adapter
and reboot and see if it Windows re-installs the adapter on its own. Be prepared to manually install the drivers. If the units can be hardwired during this procedure, keep it connected so Windows can access the internet to get drivers on its own. (( The Dell software may install from its own restore image???))
EDIT: Are you on the newest Bios for the 4 Dell's? If this hasn't been done/upgraded then you should make sure you are on the newest.