Thank you for contacting Intel Communities.
My recommendation regarding this situation would be:
1. Uninstall the driver for your wireless adapter, then restart and let windows install the default drivers.
2. If the problem persists, do the same as in step 1 but this time use the driver provided by the OEM.
3. Test the system with the Intel driver, but since this is an OEM computer we cannot assure it will work fine.
Intel(R) Dual Band Wireless-AC 7260 Bluetooth Driver (from OEM): http://downloads.dell.com/FOLDER03160651M/1/Network_Driver_PG3XR_WN32_18.104.22.168_A00.EXE
This looks like a driver like issue since you said the device works fine in another version of Windows.
The final recommendation would be to contact the customer support from the OEM, to get more troubleshooting for this situation.
The previous contact with Dell was to access their website and download drivers, which would be the reason why I am advising you to contact their support center.