If you enable ETHoA bridging on your Thompson Speedtouch to delegate the IP to a new router and you want to use the original MAC address of your Speedtouch, to make your new router get the old Internet IP of your Speedtouch or because your ISP mandates it, you need to change the MAC address of your Speedtouch.
Otherwise bridged traffic to the old MAC will be eaten by the Speedtouch instead of passing it through to your new router.
My old MAC was 00:14:7f:cf:ad:29, so I changed this to 00:14:7f:cf:ad:28 with the following:
{Administrator}[ip]=>:ip ifconfig intf=loop hwaddr=00:14:7f:cf:ad:28
{Administrator}[ip]=>:ip ifconfig intf=LocalNetwork hwaddr=00:14:7f:cf:ad:28
{Administrator}[ip]=>