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MAC address changes

B

Bill70

macrumors newbie
Original poster
Jan 5, 2022
5
0
Hi,
I have a macmini from 2011 with MacOS 10.13.6 installed, which I am just starting to use again after a few years of non-use.
I have a problem though : each time the machine restarts, I get one of 2 MAC addresses. I am not using WiFi it is always connected via ethernet cable. I either get what I presume is the correct MAC address, or a strange one starting 00:01:01:....
Nothing changes in the config - I can just restart the machine, get one MAC address, then restart without changing anything and get the other!
Its a problem, as my router is configured to auto assign IP addresses based on MAC address.
Does anyone have a solution or suggestions as to what may be causing this?
Thanks,
Bill.
 
Hi Brian,

I am determining the MAC address from various places : the Advanced page of Network Preferences, ifconfig, and my router.

WiFi is turned off, in fact I have removed wireless altogether. In Network preferences I only have 1 interface available (i.e. ethernet)

The macmini is connected via cable to a switch box (which has no configuration settings), then to my router.

Thanks,
Bill.
 
What if you go to the Advanced page of Network Preferences and change the MAC address from automatic to manual?
 
Try to disable IPv6 for Ethernet:
networksetup -setv6off Ethernet
 
chabig: I have changed MAC address config from auto to manual.

bogdanw: I have now disabled IPv6.

I will have to wait for a few reboots to see what happens as its a random thing and I cannot force it to 'go wrong'

Thank you both for your ideas and tips. I will reply with any results I get (positive or negative)
Bill.
 
Hi All,

After the suggestions by chabig and bogdanw, I still have the issue.

It seems that it only happens on first boot of the day. If I boot from cold, I will have the wrong MAC address. If I restart, it stays the same, but if I fully shutdown then restart, it gets the correct MAC address. Could this be PRAM battery? I would have thought that MAC address is hard coded to the network interface card, so PRAM battery does not really sound right to me, but I am not 100% sure.

Any further ideas?

Bill.
 
Hi Brian,
Its a Draytek Vigor2860 and I have upgraded the firmware to the most recent.
This is not the problem as the macmini should have the same MAC address regardless of whether its connected to the router or not.
 
What happens if you set the address from Terminal?
networksetup -setnetworkserviceenabled Ethernet off
sudo ifconfig en0 ether 1a:2b:3c:4d:5e:6f
networksetup -setnetworkserviceenabled Ethernet on
 
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