Inajr02's advice only applies to the new whole home premium disks because of the way the setup works is a little different to the older disks. For the older disks the correct method is to connect them all directly to the router or through a switch connected to the router.
Don't assume that your hub is part of the mesh, its just being used to provide the Internet connection, the discs are a MESH system, and your devices should move to the best disc to provide the best service, however not always the nearest.
If you are getting under -79Db signal strength that should provide a good service between discs via WiFi. if you are looking for more detail i am sure @Dan-O will expand the detail.
as to the BT complete WiFi system this has the firmware in the HUB providing the MESH connectivity ( replacing the first Disc) but remember you can't mix types on the same network.
-72dBm is still a good connection so this is why it has still chosen to connect directly to the master. If a disc connects via another disc, all network traffic needs to be transmitted and received twice instead of once on the backhaul, so it can halve your performance. This is why the system balances between stronger signal and fewer "hops" - to get the best overall performance.
There are many definitions of "mesh" system but all WHW models fulfil the principles of mesh - discs can connect to each other in various topologies, automatically switch between discs if necessary, one single SSID, steering between discs etc.
The setting is available at http://mybtdevice.home under Settings > Wi-Fi. You need to have firmware v1.02.11build02 or later to see this setting though.
None of the WHW models will result in data storms if you connect more than one via Ethernet. With Premium WHW it will show a red LED unless you connect the cable via another disc. With WHW1 or Mini WHW, you can connect multiple via Ethernet to the router. @lnajr02's diagram is the correct way to connect Premium WHW.
The minimum RSSI varies between products depending on receive sensitivity / radio performance. For backhaul signal, we've set anything better than -80 as a good signal based on performance and coverage testing. You'll see an orange LED on the disc and in the app if a disc exceeds this.
have been reading this thread with interest, this is my first post on the Community.
I am interested in Whole Home WiFi but want to be sure that it will do what I want before I buy. I have BT Smart Hub (not Smart Hub 2), and I am trying to get better WiFi coverage through the house and garden by replacing my aging Apple Airport. All rooms have wired Ethernet ports which connect to an unmanaged Cisco switch. So what I am trying to achieve is a single mesh WiFi network, with seamless handover between discs, but I also want to make use of the speed and reliability of the Ethernet ports. So if I buy a 3 disc Whole Home, can I connect each disk to the Ethernet port in the room and get it to operate as I intend ?
Thanks ! Paul