Microsoft always reserves 20% of the total bandwidth for purposes such as updating or controlling the use of computers.
To speed up the internet, you need to open the Run dialog box by pressing Windows + R key combination or click Start -> Run (in Windows XP), Start -> type Run in the Search Programs and Files box (in Windows 7, 8 or 10) and press Enter. Then enter the command gpedit.msc in the Open section of Run and click OK.
The Local Group Policy Editor window appears, you need to go to the Administrative Templates folder in the Computer Configuration section to find the Network section and click on QoS Packet Scheduler. At the QoS Packet Scheduler window on the right side of the screen double click on the Limit Reservable Bandwidth line.
In the Limit Reservable Bandwidth window you can see that this mode is set to NotConfigured but you can still set the parameter by selecting Enable. Next in the Options section, select Bandwidth limit (%) to enter that value as 0, then click OK to save the setting.
Finally, You need to Restart the computer for the change values to be set. Now your computer is considered to have fully booted 100% of bandwidth.