Voxel
Part of the Furniture
Is the onboard speed test working correctly?
In general it is OK, but OOKLA speedtest depends on server you are using for your test, its overload (e.g. could be faster in night time) etc.
Onboard test is in binary form in GPL and it uses own logic to select server, this logic is unknown for me.
You can try just several OOKLA servers selecting them manually from your browser, i.e. http://www.speedtest.net/ but not in router GUI. What is best for you.
Voxel.