Different types different set ups etc… You doing tests on cable or wireless?
I did see that written somewhere and ended up trying with cable rather than wifi, … results were better,. eg; more often showing closer to my supposed 12mb b/width,… but still some incredible variation.
The one noted is the DODO speed test. Dodo indeed.
Wifi causes all sorts of issues with speed and reliability test. Glad you got better results.