Policy based QoS not working in Windows 7 clients


Symptoms


You have a Windows 7 client machine / Windows Server 2008 R2 server on which you are pushing Policy Based QoS and setting a DSCP value for particular / all traffic.

You notice in a subsequent network trace that the DSCP value is 0x00.

Cause


This issue occurs because the DSCP value gets assigned only to the traffic on the adapter which is able to access the Domain.
For example you have two adapters with one in production and the other for a private network (maybe used for backup).
You would notice that the DSCP value gets tagged only on the traffic from the production adapter and not the backup adapter.

Resolution


If you need to DSCP values to take effect on the adapter which does not have Domain access, you need to add the following registry on the system:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\QoS

Type: REG_SZ
Name: Do not use NLA
Value: 1

Create key "QoS" if it does not exist.

After you create the above registry key, you need to reboot the computer.