@JeanGerard 

You can set different SSIDs per AP by configuring WLAN Groups or by specifying a SSID override on specific APs (Device | Config | WLAN).

Note that if you have an SSID shared between groups, roaming may not be as robust - you'll see a lot of connected/disconneted messages in the log when a client moves from one AP to another as opposed to 'roaming' messages.  That is the way I had things configured intially, but moved to a dummy/override setup for the one SSID that I needed to be exclusive to a specific AP.

https://community.tp-link.com/en/business/forum/topic/236756

@TEDC Thanks a lot! I'll have a look around. Thanks again!