Update: I found Faq #13 addresses the secondary question on IoT and GuestNetwork https://www.tp-link.com/au/support/faq/3529/ - it is not (yet) designed to be supported by SatelliteRouter The Primary...

@Kevin_Z and TP-Link team I was doing some testing on my EasyMesh setup with the HideSSID option Here's a cut and paste of the findings from the Reddit Post (...