RT-AC66U_B1 changing 5GHz MAC address?

[fonix232]

So, my landlord replaced the previous "new" router (ZyXEL Armor Z1), which had a MAC filter, and also a bug where the MAC filter did not work on 5GHz networks.

So to get around I bought this AC66U_B1 and set it up as a repeater. It worked fine. But now he replaced it with an AC51U (cheapass, right?) for "better wifi signal". But he's still making us pay for the new router...

I've tried with DD-WRT without much luck, to spoof the MAC of the 5GHz network to a device he already added to the filter. However, for some reason DD-WRT was fritzing out, basically throwing all devices off the network after some time. Probably some bug, but not one I can live with.

Since then, I've been trying to force this damn thing to cooperate. I've checked nvram, there's three variables with the value of the MAC address of the 5GHz network:

wl1_hwaddr
wl1.1_hwaddr
1:macaddr

However no matter which one I set, it simply gets erased during reboot.

Is there a way to make this permanent, or to change the MAC address permanently? No, talking to him is not an option, the "number of devices allowed on my wifi network is limited".