Received packet on lan1 with own address as source address

I am seeing this once in a while on my EdgeRouter 4:

# logread -e 'own address'
Sun Dec 13 08:53:19 2020 kern.warn kernel: [77574.952962] br-lan: received packet on lan1 with own address as source address (addr:e0:xx:xx:xx:xx:c7, vlan:0)

It looks like the LAN bridge is using the same MAC address as the lan1 interface, so I suspect that's part of the issue:

root@OpenWrt:~# ifconfig|grep E0:xx:xx:xx:xx:C7
br-lan    Link encap:Ethernet  HWaddr E0:xx:xx:xx:xx:C7  
lan1      Link encap:Ethernet  HWaddr E0:xx:xx:xx:xx:C7

Should I change the br-lan MAC address or does the bridge interface always inherit the address of the first interface it covers?

I remember it was discussed again in the past and there was no clear root cause nor solution.
Make sure there is no loop which would bring back a frame the router sent.
Verify that no lan host is trying to hijack packets by impersonating the OpenWrt.
Narrow down the potential culprits by moving devices to the other lan ports from lan1.


Some findings via forum search for own adress as source