Ya it needs to be the main router. I believe it is possible to do via the extender but it could very likely create firmware issues, so do it from the main hub to be sure. Fortunately you only need to update the apex the one time and then after that you can connect it via wifi from your house. You will have to hook it to the main hub again if there are any future updates to firmware but Apex doesnt do firmware updates very often for that very reason.