PTCL SmartTV over MikroTik Routerboard

I am trying to figure out how to have my STB connect via mikrotik router.

I have connected VDSL Modem to the WAN port of my mikrotik routerboard and my SmartTV STB is on one of the lan ports. If I create a layer 2 bridge between both WAN and LAN ports, the STB works fine, but this causes me to loose all the router functionality as it just becomes a switch.

I have tried setting up an IGMP proxy, but that doesn’t seem to work either. Has any one tested a way to make this work?