Hello and sorry if this topic or post not in required section.

My small question is the following:
I have setup pppoe client/server in Mikrotik and everything working fine, but the surprise is that, when my client disconnect his PPPOE account, he can still use the internet by setting fix IP addresses in his LAN adapter, not only that, he is able to get the full bandwidth of the Mikrotik.Let say if his PPPOE account is restricted to use shaping as: 128Kbps, when his PPPOE client disconnect and he set fix IP, he is able to get the full 2Mbps from the server.

Here is description:
PPPOE connecting, getting auto ip from Mikrotik: 172.10.20.something
Mikrotik LAN IP address: 172.10.20.1/24

So in this case, he will be able to set in his LAN adapter the following without dialing his PPPOE:

IP Address: 172.10.20.something
Gateway: 172.10.20.1
DNS: 172.10.20.1

Any solution, response will be appreciated

I suppose you have IP address set on router's ethernet interface. Remove it.
If you set local-address on PPPoE server it will automatically appear when client connect so the physical interface don't need IP.

best regards

Done.
Ive already made a new IP Pool and set it in NAT for pppoe users only