i have small pppoe server everything work fine but the problem i can ping users ip in server only but users cant ping each other , I put pppoe Clint in sxt so i cant log in the users sxt throw winbox or other way but i can access the server throw winbox, but I cant ping server also but I can access it. Any help

Are you assigning the default GW to your clients?
Do the clients have "use default GW" set to yes on their pppoe-client interface configuration?