Aggregate 3 Ethernet ports from ISP router

RouterOS
1

Hi,
Newbie here, I’m learning things to improve my home network.
Here is my problem, my ISP router is quite limited, I can’t change it’s mode to bridge for the moment because I would lost WiFi.
Plus, if I do enable bridge mode, it’ll left me with one 2.5Gb port, whereas my ISP bandwidth is 5Gb (download, upload is not concerned as it is 900Mb)

This whole bandwidth is shared between 3 ports: 1x2.5Gb, 2x1Gb, the rest is for wifi.

My idea, I don’t know if it’s possible, is to aggregate these 3 Ethernet ports to my brand new RB5009Ug.

I would then use the SFP to another switch, and the remaining 5 ports of the RB5009 for my lan.

It this possible? How can I achieve this? With ecmp?
Thanks for your help.

2

Replying to myself, I found some information.

ECMP is only when several ISP or uplinks are available, which is not my case.

What I need is bonding / LACP. But it needs to be implemented on both sides (ISP router and the Mikrotik one). My ISP’s doesn’t currently support this, so I can’t.
For anyone looking for the same info, my ISP is Free (french ISP) and the router is a Freebox Pop.