To disable the Windows 2003 Retention bandwidth Service

Windows Server 2003 retains 20% bandwidth by default, such as 100Mbps of links, maximum only to 80Mbps, and turning off the "limit retention bandwidth" service can improve network performance.

First, run the Group Policy manager

Start menu-run (or ctrl+r), enter gpedit.msc, and open the Group Policy Manager

Second, find the "Qos Packet Scheduler"

Left column to locate and click "Computer Configuration" → "Management Templates" → "Network" → "QoS Packet Scheduler"

Third, disable the "limit to retain bandwidth"

Right Bar double-click "Limit to retain bandwidth" and release all bandwidth by selecting disabled on the Settings tab