Hello,
I am an OpenWRT developer I will provide a firmware that will have a web option (a config text file as well) where you can set the destination HTTP server for the json requests.
We need to speak in details about collected data to be sent upstream. RSSI is not something you can see in the probe request, only the client knows that based on the probe reply. Device MAC is in that packet and last seen date can be stored somewhere. Device id is an additional ID besides the MAC address or is something else ?
I am available next week to work on this
Regards,
Iosif