A lot of strange problems... 2 ESP8266 with duplicate MAC addresses !

[rin67630]

I got recently a lot of strange problems:

My Arduino IDE did only display sporadically a few of the ~twenty connected ESP8266 devices as OTA candidates I have.
And once I found a match to upload, it seemed to upload, but did not.

My dashboards in the cloud displayed erratic results.
After a long troubleshooting, I finally found the very cause:

What is not supposed to happen, happened: two of my ESP devices had the same MAC-Address !
The manufacturer is supposed to guarantee that the MAC address of an ESP device is unique?
It was not !

Isn't Espressif is supposed to guarantee that the MAC address of an ESP device is unique?
It was not !

So, if your System is playing crazy and you can’t figure the cause: think to verify that you really have unique ESP MAC-Addresses in your network.
I suppose some routers will report the conflict, my AVM Fritzbox router (a reputable brand) did not…

Regards
Laszlo

[aliarifat794]

You can assign a new MAC address to avoid duplicates.

[rin67630]

You can assign a new MAC address to avoid duplicates.

It will not be permanent.
I just marked that device for use elsewhere in another network.

[AcmeUK]

You are not the first to find Duplicate MAC addresses!