internet speed is 6mb but speed test shows only 4mb

Hi, i have a problem. my internet speed is 6mb and if i speed test it on it only shows 4mb. i think some settings in router is causing this. any help would be appreciated. Thanks :).
Screenshots for internet speed and router settings is attached


No, I am living in Islamabad and getting amazing speed. PTCL is providing best services in my opinion.
if you have facing problems, you need to chat with customer care and need to resolve your problem. their services are awesome.