Hello!

I use a Draytek Vigor 130 as a modem and fire up the WAN connection by PPPoE with the router. Rightnow I am connected to a ADSL2+ line and everything works fine. I will switch over to VDSL2+ in a few weeks and for that I need to pass a VLAN Tag from the mikrotik to the modem, but I haven't found that on the PPPoE configuration page.

BR Holger

You mean that PPPoE client must work in tagged VLAN? If so, then if you now have PPPoE client on etherX, then add new VLAN to etherX and move PPPoE client from etherX to VLAN interface.