Block all on a port, read description better

Hi, I have a omnitik connected to a PTP… I have connected a client through wire on port1 (PPPoE) but by this port can see and discover all devices on lan on winbox, how I can block all access to internal network but still working the PPPoE connection of this client?

Block all except the PPPoE connection on port1 of the MK device.

Thanks!!