mac address change sometimes


sometimes when you unplug the lamp from power, and then replug the lamp get a new mac address!!
thus the lamp gets a different IP, and thus I cannot control the lamp anymore from my automation software.
Note that the last 3 part of the mac address never changes.

any idea why the mac address change like this? I only noticed 2 mac address per lamp.
Équipement 02:0F:B5:D9:31:F7
Équipement 78:11:DC:D9:31:F7

As you can see this lamp has connected with 2 different mac address thus gets the 2 IPs.
I have the same behavors with my 2 lamps (thus a tolal of 4 mac adress, 4 IPs)

My new router does not allow me to assign the same IP to 2 mac adress (it was possible with my previous one).
so I have the issue with 2 different routers, and 2 lamps.

I might have one a potential root cause.
I’m using a wifi extender netgear WN3000RP V1h2
It is configured with same SSID as my main router.
So I guess when I unplug and plug again my lamp, it might connect to one or the other.
i guess when it connects to the main wifi router, it gets the real MAC address (78:11:DC:D9:31:F7, this is the one I can see printed on the lamp), and when it connects to the extender instead, then the extender might assign another mac address? (like a virtual mac address)? thus it assigns 02:0F:B5:D9:31:F7
I have no idea why it would do that. is there a way to keep real mac address?
i will continue my investigation and share here if I find something.
worst case, I will not assign the same SSID anymore to both the extender and the router, thus I will connect explicetely each lamp to either the router or the extender. I guess then it will always either have the real mac address or ther virtual one which is fine as soon as it does not change!
however i like having the same SSID, thus my phone or tablet switch more smoothly from one to the other when I move in my house