What you are doing is not supported. Only the OEM/integrator (DELL) can make modifications/upgrades to the wireless adaptor. Installing/replacing/upgrading a wireless adaptor by the consumer is not supported.
This message was posted on behalf of Intel Corporation
As Al Hill mentioned, Intel does not support wireless integrations by end users.
To elaborate on your issue, it's important to note that WoWLAN is supported on specific OEM platforms only. You would need to check with your manufacturer to determine if your system supports the feature.
Your computer manufacturer also provides a list of pre-approved wireless adapters, and regrettably, the Intel Wireless-AC 7260 is not on the list for your particular model. x.