Ax2 dhcp offering same ip already bound to other pc

RouterOS Beginner Basics
1

hi,

regardless that i’m connecting through docking station , once i connect a different laptop dell inspirion the dhcp offers the same ip that was bound to my other pc. therefore there is like a 2 minute countdown and then it disappears from the leases of the dhcp but the ip is effectively bound to the dell. the dell is my new computer and had it configured to basically mirror office and one cloud to mu other pc

any ideas about what’s happening? there is no disswrvice just strange behavior of the dhcp server.


ciao
Antonio

2

What MAC address is being used for the DHCP offering ?

3

Hi,

thanks for this question because it was the last thing I would have imagined!!!

something strange .. it seems that both my Dell & AUS ROG have the same physical address (MAC address) : 84-3A-5B-E8-29-F7

so this explains why the DHCP assigns the same IP to the other pc when online!!

I connected the ROG & DELL on the same network and the DHCP effectively assigns a different IP to the othe PC but when only one PC is on the LAN the AX2 is assigning the same IP:
172.22.2.21

how is this possible??? what’s going on? why in the world do these PCs have the same ethernet MAC address??

is this a NON PROBLEM or is this a PROBLEM? As I mentione there is no diservice i just don’t see the lease on the DHCP form on winbox…

can this be solved?

ciao,
Antonio

4

I don’t buy that you have a casual MAC collision.

It is more likely that either of the two devices has had the MAC address manually set (cloned from the other) for one reason or the other in the past.

It is more probable that you set the MAC on the Asus Rog than on the Dell, but cannot say, it is a “normal” function of many routers, see:
https://www.asus.com/support/faq/1045126/

That address seems to be Inventec:
https://macaddress.io/mac-address-lookup/J2a1lNQ82j

5

HI Guru,

I bought the Dell last week and asked my technician to clone the two machines because i wanted the same files on both PCs and cloud… but had no idea that he had set the same MAC address on both PCs!!!

so what should I do now?

  • leaveall as is? being that in the end everything is working fine?

  • tell this information to my technician who configured the PCs?

can you suggest?

ciao,
Antonio

6

On the clone, see if there is an option in network settings to reset MAC Address.

7

You have a technician? :open_mouth:
I thought that the Asus was a router, not another PC, and, no, it is not “normal” that when “cloning” a PC also the network MAC is cloned, only the hard disk contents (and it is normally never a proper clone, strictly speaking, as drivers, the OS license and what not won’t work on two different machines).
Anyway, supposing that it is Windows 10 or 11, very likely it has only be changed in software/OS-
When you boot in Bios/Uefi you should be able to see the actual hardware MAC the network card has.
Then you can choose in software, see here (Italian) whether to change it back to the original, to the set one or to a random one:
https://www.aranzulla.it/come-cambiare-mac-address-952516.html

8

Hi Guru,

yes i have a guy that configures my PCs.

we agreed to leave as is for now even though I’m not 100% convinced that is the right thing to do..

9

Duplicate MAC addresses on the same network is never a good idea …

10

took your advice and changed it!!

thanks!

11

Ok so changed thew MAC address of the Dell PC but when the lease is finished seems that the PC yes grabs the IP address but is not showing up on the Leases of the DHCP.

so i did ipconfig /release
ipconfig /renew
it grabbed the same IP and shows on the DHCP leases.

could this be an issue linked also to the Docking station?

why my computer assigned IANA IP?