I am making some tests with my router and it looks like the mac address I change by doing:
ifconfig eth0 down
ifconfig eth0 hw ether 01:02:03:04:05:06
ifconfig eth0 up
Gets changed to the original one when connecting to the rooter. I am on ubuntu
make this new script, this will make settings permanent !
paste this code, replace mac address you want
sudo chmod 755 /etc/network/if-up.d/changemac
now disconnect the ethernet and connect again and check the mac by running
ifconfig
(I know this may not be the proper solution, but as temporary measure)
you could try fedora. in fedora you change easily change mac address from GUI and it stays persistent.
Or wait for more responses