So it seems that the issue I had with all the other Fedora versions is still present in Fedora 21. I have a Dell Laptop Latitude E6510 and on a default install connecting to wifi makes the wifi led flash on and off and quite personally it drives me nuts.
So to remind people of an old post, here’s how you fix it.
In the folder /etc/modprobe.d create a file called iwlwifi.conf and add in the following line
options iwlwifi led_mode=1
Save the file and reboot, that should stop your flashing WIFI led