I see that you TP-Link guys have implemented custom password feature for this extender with update v1.0.35 Build 241101 Rel.49351n (6985).  So thankful for this. 

But yet to see the Lock to AP feature implemented too, as requested by myself and few others. Please consider this request, this is a must have for extenders as pointed out by us. The extender decides itself to connects to other same named SSID APs  that has weaker signals and ruins the streaming speeds.

Attaching previous threads related to this; 

Mine

Some other user 1 ,   2

Daisy Onemesh extender Lock to AP