Asus Router is cloning Laptop's Mac automatically

[korndawg]

I work for an ISP and recently we've been having troubles with our Asus router cloning the Mac address of our tech's laptops and tablets. We are trying to replicate the problem but to no avail. It seems to happen randomly. The routers we have had the happen to are the RT-AC51U, RT-AC66U and the RT-AC56U. Has anyone else encountered a problem like this?

 

[ColinTaylor]

Yes I've noticed this over the last few years on the my RT-N66U and RT-AC68U running various versions of Merlin's third party Asuswrt. I've never been able to pinpoint what causes it because it happens so rarely. It only happens when I'm messing about with my WAN connection for some reason (which in itself is very rare). It might be something to do with the way the router auto-detects the WAN connection (when the WAN isn't working properly) - but that's just a guess.

 

[NGRhodes]

I seem to remember the fix being to grab the routers true mac address and put it in the mac clone box in the wan settings, save and reboot.

 

[RMerlin]

A few months back, Asus changed the WAN code so it will try different MACs if it's having issues grabbing a lease. That might be what you are experiencing there, where it might try to use a connected client to obtain a DHCP lease. I would expect a simple router reboot (without the technician's laptop connected) to fix that.

Beyond that, I haven't really studied in details Asus's changes, since they were constantly changing that part of the code at that time.

One thing for sure tho, it wasn't anything that was implemented by me, so that behaviour would be the same with the stock firmware.