Don't think this does what you think it does. If I understood correctly, this measures speed to that docker container. For e.g., if you have this docker container running on your Unraid and you visit this container's URL from your mobile phone via Wifi, then the speed you see is the speed experienced by your mobile phone when accessing the Unraid machine.
So when I visit this from my mobile phone, I see speeds ranging between 400-400 Mbps over Wifi
When I visit this connected to a 10Gbps switch, I see speeds of around 8Gbps.
If your Unraid machine is exposed to the internet, then perhaps, the docker container can be used to do an internet speed test.