Hello Victron enthusiasts,
what I observe here in my system is not creating any issue. Just wondering, why my Cerbo GX shows up with two different IPs on the same LAN port. WiFi and BT is off in my Cerbo. It’s connected via LAN cable to my router.
Find the screenshot attached. Any idea, why that is the case and for which purpose?
Thanks in advance, Andreas
Thank you @ricardocello .
Just not sure what it means for that specific scenario at the end. All other devices connected to the router do not show such an address, so pretty sure the DHCP is working. And in fact, it got a correct IP.
Moreover, it shows a different MAC address for that second “ghost” IP. Assuming, the Cerbo has only one LAN interface connected to the port, where is the other MAC coming from? 
Ok, I just checked my Cerbo GX, and it does the same thing, and it is annoying.
Including the alternate MAC address assignment.
I’m guessing the Cerbo has a bootloader that boots with one MAC address, and when VenusOS comes up, it gets a new MAC address and then gets its DHCP address.
I’ll check if any packets are transmitted after the initial bring up, but I don’t think so.
Victron people will need to answer this question.
Hi does this help explain
https://communityarchive.victronenergy.com/questions/133443/cerbo-gx-announces-two-ip-adresses.html
Yes, that covers it. Thank you!
This explanation from Victron is the solution from my point of view, yes. Thank you @nesswill
mvader (Victron Energy)
Hey all,Having two IP addresses, and even two different mac addresses on the same physical interface, aka ethernet port, is perhaps a bit unusual but also within official IP specifications and supported by many OSes and done often in for example servers.
The GX has two IP addresses on its ethernet port:
the most used one, defaults to DHCP and can also be set to a fixed IP address by the user. The mac address for this one is the one on the label and static - assigned during production.
a link local address. 169.254.xxx.xxx. The mac address for this one is a random one, generated at boot.
Though not well known in general, the link local mechanism is super useful; and we have it there - always, so also when DHCP for the other one works - to allow communication between devices to work always. Without depending on a proper functioning auto config normally done by having a dhcp server on a router.
For example on boats, this allows the MFD and the Gx to communicate and perform their functions as soon as the installer plugs both of them in a switch. No knowledge needed about IP addressing and no need for a router to be in there and working.
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