I have three Rockpi-4B SBCs. Two of them have the same ethernet MAC address.
I ordered all three from Amazon Prime individually over a period of a week. All
three arrived with two day delivery. The MACs are not marked on the SBCs or in the
boxes in which they were received.
One of the SBCs with the offending MAC (46:af:95:af:26:7c) has ended up as one of
my feeders (108954). After getting the feeder up and running I started working with the
other two SBCs. Then the weirdness started. When I finally figured out that the impossible,
duplicate MACs had, in-fact happened, my first thought was to take a sledge hammer to
the second one. Sensibility then took over and I think I will return it to Amazon as defective
under their 30 return policy and get a free replacement.
I suspected dup MACs in troubleshooting early on but did not persue it because I thought
that dup MACs would never occur. Finally it became obvious that it had to be a dup MAC
problem. A google search indicated that it is more common than most people think.
When the dups were plugged in to different switches:
Hostnames changing unexpectedly.
Failure to ssh into one or both SBCs.
“Man in the middle” alerts from ssh.
Unable to assign static IPs.
When plugged in to the same switch:
Complete lost of connections to both SBCs.
Bottom line: Beware of duplicate ethernet MACs with Rockpi4Bs.