3 Internet Connections work as 1

I am wondering if there is a way to make this scenario work.

I have 3 Internet connections 50M/4M (Download/Upload) each. So I have ether1-WAN1, ether2-WAN2, ether3-WAN3, ehter4-LAN. Is there a way to run a speedtest from my PC when connected to ether4-LAN and reach a speed of 150M/12M ?

No, that’s not possible. Well, unless your ISP agrees to aggregate (bond) these three physical links into a single logical link for you.

Thank you for the info

no. but It is possible to start 3 browsers, test simultaneously and get 50 in each though.
if interested, start here:
https://wiki.mikrotik.com/wiki/Manual:PCC

Or run 3 tunnels somewhere where you can bond back the traffic together…