How to configure mikrotik with pppoe wan. I have a ONU Router provided by my ISP and it is configured to connect to internet via PPPoE and i want to connect internet directly Via mikrotik using LAN port of the ONU Router as i dont want to use any media converters.

Setup your isp router as a bridge. Then,
the simple way is to enter quick config on mikrotik and setup your pppoe connection there. This way all your firewall rules will adapt to pppoe interface and not to ether1 , leaving your router exposed to the internet. The other way is to set up pppoe connection manualy in interfaces tab but then you will have to setup manualy your firewall rules.

Setup your isp router as a bridge. Then,
the simple way is to enter quick config on mikrotik and setup your pppoe connection there. This way all your firewall rules will adapt to pppoe interface and not to ether1 , leaving your router exposed to the internet. The other way is to set up pppoe connection manualy in interfaces tab but then you will have to setup manualy your firewall rules.

Do i also have to disable any features on ONU Router?

I don`t know what features has the router but setting it as bridge will make it transparent, also will disable any services running on it, it will act as a switch between mikrotik and your isp.

thank you for giving your time and for writing here. I have finally done it. THANK YOU.