PPPOE problem!!

HEllo,

I have a problem with pppoe client.
My clients have linksys router as pppoe client.
All works fine.
The router connect with MT without problems.
Sometimes have the linksys router a problem.
It tries to develop several connections within fewer seconds until the limit is reached.
Can I limit the connection on three per user?
When I have the problem, I see the MAC address from client.

I hope, you understand my problem.