How to configure RB4011 with a VLAN switch for 2.5G？

RouterOS Beginner Basics
1

I have a RB4011 router and it works fine with 1Gbps network.
Recently I have considered upgrading to 2Gbps bandwidth. But there’s only one SFP+ port on RB4011 which can exceed 2.5Gbps+.
I searched for some old articles. They tell me it would work that RB4011 configured as Router-on-a-stick like this:

fiber modem <-----2.5Glan----> Vlan Switch <----SFP±—> RB4011
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2.5G Clients

The fiber modem is bridged to switch.Then the router dial a PPPoE connection. None of the 1Gbps port on router is used. The public and local network are both 2.5Gbps.
However they didn’t provide any configuration steps. I’m new to RouterOS advanced configuration. Can anyone help me?

2

Have a look at the excelent tutorial on how to do VLANs on Routeros, in particular Router on a Stick section.

Switch has to be configured appropriately as well. If fiber modem works as untagged device, then configure switch port connecting it with “default vlan id” (or PVID) so that switch taes care of tagging/untagging WAN traffic. Etc.