My solution is remove the kernel module (in my case it is ath5k.ko, as it is
an Atheros card). Removing it with "rmmod ath5k", and when I need to use it
again, I restart it using "modprobe ath5k".
If you are wired connected, you can try "ifconfig eth0 down" or whatever your
ethernet card is named (could be something like enp0s10 or similar, if you are
using predictable names).