Dual-band wi-fi dongle needed for DELL Optiplex 7050 running Siduction

[WetGeek]

The Optiplex that I use for a media streaming machine uses a 2.4 GHz dongle for wi-fi.  I want to upgrade that to a dual-band dongle, but I've already bought three of them -- that supposedly support Linux -- and not one has been recognized by the computer.  It just reports "no wi-fi device found."

If anyone here is using an Optiplex with a dual-band wi-fi dongle, could you please let me know what brand it is?  I really don't want to buy a fourth one that the computer won't recognize.  Thanks for any help with this.