Philosophical question Let ' s say that I went back in time , and made your dad infertile . Your mom and dad had artificial insemination done , and you were still born . Are you still you ? <| sep |> The bug is that we use STP to determine the boundaries of switched L 2 segments on wired ethernet . Annoyingly , some switches default to a setting called STP root protection which causes them to silently drop STP traffic if they receive it from a client port , which means that the mapping process fails as a consequence , layer 2 loops are formed because the eeros don ' t know they ' re all on the same layer 2 segment . The eeros use priority 0 x 8000 , which is the default priority for a lot of devices , which means they only trigger this bug if your switch has a MAC address lower than the eero , so we didn ' t see this in any of our testing the eero OUI is 1422 db , which is fairly low . This only happens if more than one eero is connected to a single switch , that switch supports STP , and that switch is configured to do this root protection thing , and its MAC address happens to be lower than eero ' s . And we will be fixing it by increasing our root priority setting so that the default setting on other switches doesn ' t conflict with it in the next release .