Without WDS - AP bridge

Dear friends, I have an app running as a bridge (RB411AH - version 5.10) and two cpe function as clients (SXT - version 4.14).

First question:

It is this, how I can do for customers CPE can not be seen each other in order to isolate the DHCP generation of each respectively.

I have tried disabling “default forward”, but then only I can ping from the AP to the clients but not from the clients to the AP.

Second Question:

You can configure a Bridge AP and CPE as customers used pure without WDS, configure it happens that I can not ping from either end, it is noteworthy that using WDS everything works normally.

Greetings and thanks for your replies.

Kilamo