For ROS Bandwidth Test you can use Tom Jones (from North Idaho 
) public test server, see: http://forum.mikrotik.com/t/public-mikrotik-bandwidth-test-server-s-now-shutdown-as-of-april-1st-2025/94863/1
Or you can setup your own on remote site with public access to Bandwidth Test ports, for eg. on CHR running somewhere on VM.
Also MT Bandwidth test Windows application (GENERAL section) can be used for such purpose, it can be act as server or client running on machine connected on different internet connection than router with more bandwidth than you have on router, ofc. ports needs to be exposed for side which will be server (better on machine with more CPU power).
In your case I don’t believe you will have better results with ROS Bandwidth Test than with any other common public speed tests.