How to use PPPoE and lan-wan bridge on the same port?

I use Turris Omnia connected to ISP with PPPoE. The same wire is used to deliver IPTV to the STB. Previously it worked on TP-Link WR1043ND with the default firmware, where you just pick up the desired port for IPTV, and that’s it. Now, if I start lan0 (or lan4) bridge to wan, STB on lan0 (or lan4) starts showing IPTV, while PPPoE loses connection.

I asked this question to OpenWRT and they give me some tutorial, but I don’t know how to implement all these tagged-untagged things with LuCi which has no «Switch» tab anymore.

My ISP just says it is VLAN 2014 used both for Internet and unicast IPTV on my port but they have no idea how to configure Omnia properly. Can someone help me, please?