I don't believe roaming, fast or otherwise is dependent on the switch configuration. As long as the VLANs are correct, the SSID on the AP should do it's thing.

You do not have to adopt the switch, it can stay in standalone mode.

@.AT It is still a problem across ALL TPlink routers as far as I know, here's my venerable ER605v1's graph...look familar (gap was the last Disconnect period)?

@Eisen Also, if you turn on the 'Link Labels' in your topology/mapping you can see more detail on the connection:

@Eisen If the Mesh signal is weak or suffering interference then either of these will cause the isolation issue. I noticed a degradation in the mesh backhaul when it's very humid or there is active...

Do you mean 'Clients'? If you are just trying to get rid of the clients and their history data, just backup your controller without data, reset the controller, and then restore it.